Polyimide precursor, polyimide, polyimide film, varnish, and substrate

ABSTRACT

A polyimide precursor comprising at least one repeating unit represented by the following chemical formula (5): 
     
       
         
         
             
             
         
       
     
     in which A 3  is a divalent group of an aromatic diamine or an aliphatic diamine, from which amino groups have been removed; and X 3  and Y 3  are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and/or at least one repeating unit represented by the following chemical formula (6): 
     
       
         
         
             
             
         
       
     
     in which A 3  is a divalent group of an aromatic diamine or an aliphatic diamine, from which amino groups have been removed; and X 4  and Y 4  are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.

TECHNICAL FIELD

The present invention relates to a polyimide having excellent propertiessuch as transparency, bending resistance and high heat resistance, andhaving a very low coefficient of linear thermal expansion up to a hightemperature; and a precursor thereof. The present invention also relatesto a polyimide film, a varnish comprising a polyimide precursor or apolyimide, and a substrate.

BACKGROUND ART

With the coming of an advanced information society, the developments ofoptical materials such as an optical fiber and an optical waveguide inthe field of optical communications, and optical materials such as aliquid crystal oriented film and a protective film for a color-filter inthe field of display devices has recently advanced. In the field ofdisplay devices, in particular, a plastic substrate which islight-weight and excellent in flexibility has been studied as analternative to a glass substrate, and the development of a display whichis capable of being bent and rolled has been intensively conducted.Accordingly, there is need for a higher-performance optical materialwhich may be used for such purposes.

Aromatic polyimides are intrinsically yellowish-brown-colored due to theintramolecular conjugation and the formation of charge-transfercomplexes. Consequently, as a means of reducing coloring, methods ofdeveloping transparency, for example, by introducing fluorine atom intothe molecule, imparting flexibility to the main chain, introducing abulky group as a side chain, or the like to suppress the intramolecularconjugation and the formation of charge-transfer complexes are proposed.In addition, methods of developing transparency by the use of asemi-alicyclic or wholly-alicyclic polyimide which do not formcharge-transfer complexes in principle are also proposed.

Patent Literature 1 discloses that a thin-film transistor substrate isobtained by forming a thin-film transistor on a film substrate of atransparent polyimide in which the residue of the tetracarboxylic acidcomponent is an aliphatic group by the use of a conventionalfilm-forming process in order to obtain a thin, light-weight andbreak-proof active matrix display device. The polyimide concretely usedherein is prepared from 1,2,4,5-cyclohexane tetracarboxylic dianhydrideas the tetracarboxylic acid component and 4,4′-diaminodiphenyl ether asthe diamine component.

Patent Literature 2 discloses a process for producing a colorlesstransparent resin film formed of a polyimide having excellentcolorlessness/transparency, heat resistance and flatness, which is usedfor a transparent substrate for a liquid crystal display device or anorganic EL display device, a thin-film transistor substrate, a flexiblewiring substrate, and the like, by a solution-casting method using aparticular drying step.

The polyimide used herein is prepared from 1,2,4,5-cyclohexanetetracarboxylic dianhydride as the tetracarboxylic acid component andα,α′-bis(4-aminophenyl)-1,4-diisopropylbenzene and4,4′-bis(4-aminophenoxy)biphenyl as the diamine component, and the like.

Patent Literatures 3 and 4 disclose polyimides which are soluble inorganic solvents, and prepared using dicyclohexyl tetracarboxylic acidas the tetracarboxylic acid component and diaminodiphenyl ether,diaminodiphenyl methane, 1,4-bis(4-aminophenoxy)benzene,1,3-bis(4-aminophenoxy)benzene,2,2-bis[4-(4-aminophenoxyl)phenyl]propane,bis[4-(4-aminophenoxyl)phenyl]sulfone,bis[4-(4-aminophenoxyl)phenyl]ether or m-phenylenediamine as the diaminecomponent.

Such a semi-alicyclic polyimide, in which an alicyclic tetracarboxylicdianhydride is used as the tetracarboxylic acid component and anaromatic diamine is used as the diamine component, combinestransparency, bending resistance and high heat resistance. However, sucha semi-alicyclic polyimide generally has a great coefficient of linearthermal expansion of 50 ppm/K or more, and therefore the difference incoefficient of linear thermal expansion between a semi-alicyclicpolyimide and a conductive material such as a metal is great, and atrouble such as an increase in warpage may occur during the formation ofa circuit board, and there has been a problem of not easily performing aprocess for forming a fine circuit for use in a display, or the like, inparticular.

Patent Literature 5 discloses a polyimide obtained from an alicyclicacid dianhydride containing ester bond and a varied aromatic diamine,and the polyimide of Example 4, for example, has a coefficient of linearthermal expansion at 100° C. to 200° C. of not more than 50 ppm/K.However, the polyimide has a glass-transition temperature of about 300°C., and it is assumed that the film softens and the coefficient oflinear thermal expansion becomes much greater at a higher temperature,and there is a risk that a trouble occurs in a process for forming acircuit, which requires low thermal expansibility at a high temperature,as well as at a low temperature.

Non Patent Literature 1 discloses a polyimide prepared usingnorbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicdianhydride as the tetracarboxylic acid component. Non Patent Literature1 discloses that the polyimide has high heat resistance and also has ahigh glass-transition temperature. Moreover, Non Patent Literature 1discloses that thenorbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicdianhydride used herein comprises six types of stereoisomers.

Patent Literature 6 discloses a polyimide prepared usingnorbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicdianhydride and 4,4′-oxydianiline, and the like. However, no mention ismade of steric structure ofnorbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicdianhydride.

CITATION LIST Patent Literature

Patent Literature 1: JP-A-2003-168800

Patent Literature 2: WO 2008/146637

Patent Literature 3: JP-A-2002-69179

Patent Literature 4: JP-A-2002-146021

Patent Literature 5: JP-A-2008-31406

Patent Literature 6: WO 2011/099518

Non Patent Literature

Non Patent Literature 1: KOBUNSHI RONBUNSHU (Japanese Journal of PolymerScience and Technology), Vol. 68, No. 3, P. 127-131 (2011)

SUMMARY OF INVENTION Technical Problem

The present invention was made in view of the circumstances as describedabove, and an object thereof is to provide a polyimide prepared using analicyclic tetracarboxylic dianhydride as the tetracarboxylic acidcomponent and an aromatic diamine as the diamine component, which hashigh transparency and high heat resistance, and has a low coefficient oflinear thermal expansion up to a high temperature, as well as at a lowtemperature.

In other words, an object of the present invention is to provide apolyimide having excellent properties such as high transparency, bendingresistance and high heat resistance, and having a very low coefficientof linear thermal expansion up to a high temperature; and a precursorthereof.

Solution to Problem

The present invention relates to the following items.

[1] A polyimide precursor comprising at least one repeating unitrepresented by the following chemical formula (1):

wherein A₁ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed; and X₁ and Y₁ areeach independently hydrogen, an alkyl group having 1 to 6 carbon atoms,or an alkylsilyl group having 3 to 9 carbon atoms, wherein the totalcontent of the repeating units represented by the chemical formula (1)is 50 mol % or more based on the total repeating units.

[2] The polyimide precursor as described in [1], wherein the polyimideprecursor comprises at least one repeating unit of the chemical formula(1) in which A₁ is a group represented by the following chemical formula(2):

wherein m₁ and n₁ are integers of 0 or more, and mz₁ independentlyrepresents 0 to 3 and n₁ independently represents 0 to 3; V₁, U₁ and T₁each independently represent at least one selected from the groupconsisting of hydrogen atom, methyl group and trifluoromethyl group; andZ₁ and W₁ each independently represent direct bond, or at least oneselected from the group consisting of groups represented by theformulas: —NHCO—, —CONH—, —COO— and —OCO—.

[3] The polyimide precursor as described in [2], wherein the polyimideprecursor comprises at least two of repeating units of the chemicalformula (1) in which A₁ is a group represented by the chemical formula(2).

[4] A polyimide precursor comprising at least one repeating unitrepresented by the following chemical formula (3):

wherein A₂ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed; and X₂ and Y₂ areeach independently hydrogen, an alkyl group having 1 to 6 carbon atoms,or an alkylsilyl group having 3 to 9 carbon atoms,

wherein the total content of the repeating units represented by thechemical formula (3) is 30 mol % or more based on the total repeatingunits.

[6] The polyimide precursor as described in [4], wherein the polyimideprecursor comprises at least one repeating unit of the chemical formula(3) in which A₂ is a group represented by the following chemical formula(4):

wherein m₂ and n₂ are integers of 0 or more, and m₂ independentlyrepresents 0 to 3 and n₂ independently represents 0 to 3; V₂, U₂ and T₂each independently represent at least one selected from the groupconsisting of hydrogen atom, methyl group and trifluoromethyl group; andZ₂ and W₂ each independently represent direct bond, or at least oneselected from the group consisting of groups represented by theformulas: —NHCO—, —CONH—, —COO— and —OCO—.

[6] The polyimide precursor as described in [5], wherein the polyimideprecursor comprises at least two of repeating units of the chemicalformula (3) in which A₂ is a group represented by the chemical formula(4).

[7] A polyimide precursor comprising at least one of repeating unitsrepresented by the following chemical formula (5) and the followingchemical formula (6):

wherein A₃ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed; and X₃ and Y₃ areeach independently hydrogen, an alkyl group having 1 to 6 carbon atoms,or an alkylsilyl group having 3 to 9 carbon atoms,

wherein A₃ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed; and X₄ and Y₄ areeach independently hydrogen, an alkyl group having 1 to 6 carbon atoms,or an alkylsilyl group having 3 to 9 carbon atoms,

wherein the total content of the repeating units represented by thechemical formula (5) and the chemical formula (6) is 80 mol % or morebased on the total repeating units.

[8] The polyimide precursor as described in [7], wherein the polyimideprecursor comprises at least one repeating unit of the chemical formula(5) in which A₃ is a group represented by the following chemical formula(7) and/or at least one repeating unit of the chemical formula (6) inwhich A₃ is a group represented by the following chemical formula (7):

wherein m₃ and n₃ are integers of 0 or more, and m₃ independentlyrepresents 0 to 3 and n₃ independently represents 0 to 3; V₃, U₃ and T₃each independently represent at least one selected from the groupconsisting of hydrogen atom, methyl group and trifluoromethyl group; andZ₃ and W₃ each independently represent direct bond, or at least oneselected from the group consisting of groups represented by theformulas: —NHCO—, —CONH—, —COO— and —OCO—.

[9] The polyimide precursor as described in [8], wherein the polyimideprecursor comprises at least two of repeating units of the chemicalformula (5) or the chemical formula (6) in which A₃ is a grouprepresented by the chemical formula (7).

[10] The polyimide precursor as described in any one of [7] to [9],wherein the total content of the repeating units represented by thechemical formula (5) is 50 mol % or more based on the total repeatingunits, and the total content of the repeating units represented by thechemical formula (6) is 30 mol % or more based on the total repeatingunits.

[11] A polyimide comprising at least one repeating unit represented bythe following chemical formula (8):

wherein B₁ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed,

wherein the total content of the repeating units represented by thechemical formula (8) is 50 mol % or more based on the total repeatingunits.

[12] The polyimide as described in [11], wherein the polyimide comprisesat least one repeating unit of the chemical formula (8) in which B₁ is agroup represented by the following chemical formula (9):

wherein m₄ and n₄ are integers of 0 or more, and m₄ independentlyrepresents 0 to 3 and n₄ independently represents 0 to 3; V₄, U₄ and T₄each independently represent at least one selected from the groupconsisting of hydrogen atom, methyl group and trifluoromethyl group; andZ₄ and W₄ each independently represent direct bond, or at least oneselected from the group consisting of groups represented by theformulas: —NHCO—, —CONH—, —COO— and —OCO—.

[13] A polyimide comprising at least one repeating unit represented bythe following chemical formula (10):

wherein B₂ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed,

wherein the total content of the repeating units represented by thechemical formula (10) is 30 mol % or more based on the total repeatingunits.

[14] The polyimide as described in [131], wherein the polyimidecomprises at least one repeating unit of the chemical formula (10) inwhich B₂ is a group represented by the following chemical formula (11):

wherein m₅ and n₅ are integers of 0 or more, and m₅ independentlyrepresents 0 to 3 and n₅ independently represents 0 to 3; V₅, U₅ and T₅each independently represent at least one selected from the groupconsisting of hydrogen atom, methyl group and trifluoromethyl group; andZ₅ and W₅ each independently represent direct bond, or at least oneselected from the group consisting of groups represented by theformulas: —NHCO—, —CONH—, —COO— and —OCO—.

[15] A polyimide comprising at least one of repeating units representedby the following chemical formula (12) and the following chemicalformula (13):

wherein B₃ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed,

wherein B₃ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed,

wherein the total content of the repeating units represented by thechemical formula (12) and the chemical formula (13) is 80 mol % or morebased on the total repeating units.

[16] The polyimide as described in [15], wherein the polyimide comprisesat least one repeating unit of the chemical formula (12) in which B₃ isa group represented by the following chemical formula (14) and/or atleast one repeating unit of the chemical formula (13) in which B₃ is agroup represented by the following chemical formula (14):

wherein m₆ and no are integers of 0 or more, and m₆ independentlyrepresents 0 to 3 and n₆ independently represents 0 to 3; V₆, U₆ and T₆each independently represent at least one selected from the groupconsisting of hydrogen atom, methyl group and trifluoromethyl group; andZ₆ and W₆ each independently represent direct bond, or at least oneselected from the group consisting of groups represented by theformulas: —NHCO—, —CONH—, —COO— and —OCO—.

[17] The polyimide as described in [15] or [16], wherein the totalcontent of the repeating units represented by the chemical formula (12)is 50 mol % or more based on the total repeating units, and the totalcontent of the repeating units represented by the chemical formula (13)is 30 mol % or more based on the total repeating units.

[18] A polyimide obtained from the polyimide precursor as described inany one of [1] to [10].

[19] A polyimide film obtained from the polyimide precursor as describedin any one of [1] to [10].

[20] A varnish comprising the polyimide precursor as described in anyone of [1] to [10], or the polyimide as described in any one of [11] to[18].

[21] A polyimide film obtained using a varnish comprising the polyimideprecursor as described in any one of [1] to [10], or the polyimide asdescribed in any one of [11] to [18].

[22] A substrate for a display, a touch panel or a solar battery formedof the polyimide obtained from the polyimide precursor as described inany one of [1] to [10], or the polyimide as described in any one of [11]to [18].

Advantageous Effects of Invention

According to the present invention, there may be provided a polyimidehaving excellent properties such as high transparency, bendingresistance and high heat resistance, and having a very low coefficientof linear thermal expansion up to a high temperature; and a precursorthereof. The polyimide obtained from the polyimide precursor of thepresent invention, and the polyimide of the present invention have hightransparency and a low coefficient of linear thermal expansion up to ahigh temperature, which allows easy formation of a fine circuit, andtherefore the polyimides may be suitably used for the formation of asubstrate for use in a display, or the like. In addition, the polyimidesof the present invention may also be suitably used for the formation ofa substrate for a touch panel or a solar battery.

DESCRIPTION OF EMBODIMENTS

The polyimide precursor (A-1) of the first invention is a polyimideprecursor comprising at least one repeating unit represented by thechemical formula (1). The chemical formula (1), however, indicates thatin two norbornane rings (bicyclo[2.2.1]heptane), the acid group ineither 5-position or 6-position reacts with an amino group to form anamide bond (—CONH—) and the other is a group represented by the formula:—COOX₁ or a group represented by the formula: —COOY₁, both of which donot form an amide bond. The chemical formula (1) includes all of thefour structural isomers, that is,

(i) the one having a group represented by the formula: —COOX₁ in the5-position and a group represented by the formula: —CONH— in the6-position, and having a group represented by the formula: —COOY₁ in the5″-position and a group represented by the formula: —CONH-A₁- in the6″-position;

(ii) the one having a group represented by the formula: —COOX₁ in the6-position and a group represented by the formula: —CONH— in the5-position, and having a group represented by the formula: —COOY₁ in the5″-position and a group represented by the formula: —CONH-A₁- in the6″-position;

(iii) the one having a group represented by the formula: —COOX₁ in the5-position and a group represented by the formula: —CONH— in the6-position, and having a group represented by the formula: —COOY₁ in the6″-position and a group represented by the formula: —CONH-A₁- in the5″-position; and

(iv) the one having a group represented by the formula: —COOX₁ in the6-position and a group represented by the formula: —CONH— in the5-position, and having a group represented by the formula: —COOY₁ in the6″-position and a group represented by the formula: —CONH-A₁- in the5″-position. In other words, the polyimide precursor (A-1) of thepresent invention is a polyimide precursor obtained from

a tetracarboxylic acid component comprisingtrans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like (The term “tetracarboxylic acid, or the like” meanstetracarboxylic acid, and tetracarboxylic acid derivatives includingtetracarboxylic dianhydride, tetracarboxylic acid silyl ester,tetracarboxylic acid ester and tetracarboxylic acid chloride) and

a diamine component comprising an aromatic diamine or an aliphaticdiamine, preferably an aromatic diamine.

As the tetracarboxylic acid component to provide a repeating unit of thechemical formula (1),trans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like may be used alone or in combination of a plurality oftypes.

As for the polyimide precursor (A-1) of the first invention, the totalcontent of the repeating units represented by the chemical formula (1)is 50 mol % or more based on the total repeating units. In other words,the polyimide precursor (A-1) of the first invention preferablycomprises one or more repeating units represented by the chemicalformula (1) in an amount of 50 mol % or more, more preferably 55 mol %or more, more preferably 60 mol % or more, particularly preferably 63mol % or more, in total based on the total repeating units.

As the diamine component to provide a repeating unit of the chemicalformula (1), aromatic diamines which provide the one in which A₁ is agroup represented by the chemical formula (2), and other aromatic oraliphatic diamines other than these diamines may be used.

The diamine component to provide a repeating unit of the chemicalformula (1) in which A₁ is a structure of the chemical formula (2) hasan aromatic ring, and when the diamine component has a plurality ofaromatic rings, the aromatic rings are each independently linked to eachother by direct bond, amide bond, or ester bond. When the aromatic ringsare linked at the 4-position relative to the amino group or the linkinggroup between the aromatic rings, the obtained polyimide has a linearstructure and may have low linear thermal expansibility, although thelinking position of the aromatic rings is not limited thereto.Meanwhile, the aromatic ring may be substituted by methyl ortrifluoromethyl. The substitution position is not particularly limited.

Examples of the diamine component to provide a repeating unit of thechemical formula (1) in which A₁ is a structure of the chemical formula(2) include, but not limited to, p-phenylenediamine, m-phenylenediamine,benzidine, 3,3′-diamino-biphenyl, 2,2′-bis(trifluoromethyl)benzidine,3,3′-bis(trifluoromethyl)benzidine, m-tolidine, 4,4′-diaminobenzanilide,3,4′-diaminobenzanilide, N,N′-bis(4-aminophenyl)terephthalamide,N,N′-p-phenylene bis(p-aminobenzamide),4-aminophenoxy-4-diaminobenzoate, bis(4-aminophenyl)terephthalate,biphenyl-4,4′-dicarboxylic acid bis(4-aminophenyl)ester, p-phenylenebis(p-aminobenzoate),bis(4-aminophenyl)-[1,1′-biphenyl]-4,4′-dicarboxylate, and[1,1′-biphenyl]-4,4′-diyl bis(4-aminobenzoate). The diamine componentmay be used alone or in combination of a plurality of types. Among them,p-phenylenediamine, m-tolidine, 4,4′-diaminobenzanilide,4-aminophenoxy-4-diaminobenzoate, 2,2′-bis(trifluoromethyl)benzidine,benzidine, N,N′-bis(4-aminophenyl)terephthalamide, andbiphenyl-4,4′-dicarboxylic acid bis(4-aminophenyl)ester are preferred,and p-phenylenediamine, 4,4′-diaminobenzanilide, and2,2′-bis(trifluoromethyl)benzidine are more preferred. Whenp-phenylenediamine, 4,4′-diaminobenzanilide, or2,2′-bis(trifluoromethyl)benzidine is used as the diamine component, theobtained polyimide may combine high heat resistance and high lighttransmittance. These diamines may be used alone or in combination of aplurality of types. In one embodiment, the one in which the diaminecomponent is only 4,4′-diaminobenzanilide singly may be excluded. In oneembodiment, the one in which the diamine component is a combination of4,4′-diaminobenzanilide and a diamine component which provides arepeating unit of the chemical formula (1) in which A₁ is a structureother than the chemical formula (2) (other diamines other than thediamine component which provides the one in which A₁ is a structure ofthe chemical formula (2)) may be excluded. Meanwhile, o-tolidine is notpreferred because it is highly hazardous.

As the diamine component to provide a repeating unit of the chemicalformula (1), other diamines other than the diamine component whichprovides the one in which A₁ is a structure of the chemical formula (2)may be used in combination therewith. As the other diamine component,other aromatic or aliphatic diamines may be used. Examples of the otherdiamine component include 4,4′-oxydianiline, 3,4′-oxydianiline,3,3′-oxydianiline, bis(4-aminophenyl)sulfide, p-methylenebis(phenylenediamine), 1,3-bis(4-aminophenoxy)benzene,1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene,2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane,2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone,3,3-bis((aminophenoxy)phenyl)propane,2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane,bis(4-(4-aminophenoxyl)diphenyl)sulfone,bis(4-(3-aminophenoxyl)diphenyl)sulfone, octafluorobenzidine,3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diaminobiphenyl,3,3′-difluoro-4,4′-diaminobiphenyl, 9,9-bis(4-aminophenyl)fluorene,4,4′-bis(4-aminophenoxy)biphenyl, 4,4′-bis(3-aminophenoxy)biphenyl,1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane,1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane,1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane,1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane,1,4-diamino-2-tert-butylcyclohexane, 1,2-diaminocyclohexane, and1,4-diaminocyclohexane, and derivatives thereof. These may be used aloneor in combination of a plurality of types.

The polyimide precursor (A-1) of the first invention preferablycomprises at least one repeating unit of the chemical formula (1) inwhich A₁ is a group represented by the chemical formula (2). In otherwords, the diamine component to provide a repeating unit of the chemicalformula (1) preferably comprises a diamine component to provide arepeating unit of the chemical formula (1) in which A₁ is a structure ofthe chemical formula (2). When the diamine component to provide A₁ inthe chemical formula (1) is a diamine component to provide a structureof the chemical formula (2), the heat resistance of the obtainedpolyimide may be improved.

As for the polyimide precursor (A-1) of the first invention, the ratioof the diamine component to provide a structure of the chemical formula(2) may be preferably 50 mol % or more, more preferably 70 mol % ormore, more preferably 80 mol % or more, further preferably 90 mol % ormore, particularly preferably 100 mol %, in total based on 100 mol % ofthe diamine component to provide A₁ in the chemical formula (1). Inother words, the ratio of one or more repeating units of the chemicalformula (1) in which A₁ is a structure of the chemical formula (2) ispreferably 50 mol % or more, more preferably 70 mol % or more, morepreferably 80 mol % or more, further preferably 90 mol % or more,particularly preferably 100 mol %, in total based on the total repeatingunits represented by the chemical formula (1). When the ratio of thediamine component to provide a structure of the chemical formula (2) isless than 50 mol %, the coefficient of linear thermal expansion of theobtained polyimide may be greater. In one embodiment, in view of themechanical properties of the obtained polyimide, the ratio of thediamine component to provide a structure of the chemical formula (2) maybe preferably 80 mol % or less, more preferably 90 mol % or less, orless than 90 mol %, in total based on 100 mol % of the diamine componentto provide A₁ in the chemical formula (1). For example, other aromaticor aliphatic diamines such as 4,4′-oxydianiline may be used preferablyin an amount of less than 20 mol %, more preferably not more than 10 mol%, more preferably less than 10 mol %, based on 100 mol % of the diaminecomponent to provide a repeating unit of the chemical formula (1).

The polyimide precursor (A-1) of the first invention preferablycomprises at least two types of repeating units of the chemical formula(1) in which A₁ is a group represented by the chemical formula (2). Inother words, the diamine component to provide a repeating unit of thechemical formula (1) preferably comprises at least two types of diaminecomponents to provide a repeating unit of the chemical formula (1) inwhich A₁ is a structure of the chemical formula (2). When the diaminecomponent to provide A₁ in the chemical formula (1) comprises at leasttwo types of diamine components to provide a structure of the chemicalformula (2), the balance between high transparency and low linearthermal expansibility of the obtained polyimide may be achieved (thatis, a polyimide having high transparency and low coefficient of linearthermal expansion may be obtained).

The polyimide precursor (A-1) of the first invention more preferablycomprises

(i) at least one type of repeating unit (1-1) of the chemical formula(1) in which A₁ is a structure of the chemical formula (2) in which m₁and/or n₁ is 1 to 3; and Z₁ and/or W₁ each independently is —NHCO—,—CONH—, —COO— or —OCO—, and

(ii) at least one type of repeating unit (1-2) of the chemical formula(1) in which A₁ is a structure of the chemical formula (2) in which m₁and n₁ are 0, or a structure of the chemical formula (2) in which m₁and/or n₁ is 1 to 3; and Z₁ and W₁ are direct bond.

As the repeating unit (1-1), a repeating unit of the chemical formula(1) in which A₁ is a group represented by any one of the followingchemical formulas (D-1) to (D-3) is preferred, and a repeating unit ofthe chemical formula (1) in which A₁ is a group represented by any oneof the following chemical formulas (D-1) to (D-2) is more preferred. Thediamine component to provide a repeating unit of the chemical formula(1) in which A₁ is a group represented by the following chemical formula(D-1) or the following chemical formula (D-2) is4,4′-diaminobenzanilide, and the diamine component to provide arepeating unit of the chemical formula (1) in which A₁ is a grouprepresented by the following chemical formula (D-3) isbis(4-aminophenyl)terephthalate. These diamines may be used alone or incombination of a plurality of types.

As the repeating unit (1-2), a repeating unit of the chemical formula(1) in which A₁ is a group represented by any one of the followingchemical formulas (D-4) to (D-6) is preferred, and a repeating unit ofthe chemical formula (1) in which A₁ is a group represented by any oneof the following chemical formulas (D-4) to (D-5) is more preferred. Thediamine component to provide a repeating unit of the chemical formula(1) in which A₁ is a group represented by the following chemical formula(D-4) is p-phenylenediamine, and the diamine component to provide arepeating unit of the chemical formula (1) in which A₁ is a grouprepresented by the following chemical formula (D-5) is2,2′-bis(trifluoromethyl)benzidine, and the diamine component to providea repeating unit of the chemical formula (1) in which A₁ is a grouprepresented by the following chemical formula (D-6) is m-tolidine. Thesediamines may be used alone or in combination of a plurality of types.

It is preferred that, in the polyimide precursor (A-1) of the firstinvention, the ratio of one or more repeating units (1-1) is 30 mol % ormore and 70 mol % or less in total based on the total repeating unitsrepresented by the chemical formula (1), and the ratio of one or morerepeating units (1-2) is 30 mol % or more and 70 mol % or less in totalbased on the total repeating units represented by the chemical formula(1). It is particularly preferred that the ratio of one or morerepeating units (1-1) is 40 mol % or more and 60 mol % or less in totalbased on the total repeating units represented by the chemical formula(1), and the ratio of one or more repeating units (1-2) is 40 mol % ormore and 60 mol % or less in total based on the total repeating unitsrepresented by the chemical formula (1). In one embodiment, the ratio ofthe repeating unit (1-1) is more preferably less than 60 mol %, morepreferably not more than 50 mol %, particularly preferably not more than40 mol %, in total based on the total repeating units represented by thechemical formula (1). Additionally, in one embodiment, the polyimideprecursor may preferably comprise other repeating units represented bythe chemical formula (1) other than the repeating unit (1-1) and therepeating unit (1-2) (for example, the one in which A₁ has a pluralityof aromatic rings and the aromatic rings are linked to each other byether bond (—O—)) preferably in an amount of less than 20 mol %, morepreferably not more than 10 mol %, particularly preferably less than 10mol %, based on the total repeating units represented by the chemicalformula (1). Additionally, in one embodiment, it may be also preferredthat the ratio of one or more repeating units (1-1) is 20 mol % or moreand 80 mol % or less in total based on the total repeating unitsrepresented by the chemical formula (1), and the ratio of one or morerepeating units (1-2) is 20 mol % or more and 80 mol % or less in totalbased on the total repeating units represented by the chemical formula(1).

In the polyimide precursor (A-1) of the first invention, the diaminecomponent to provide A₁ in the chemical formula (1) (diamine componentto provide a repeating unit of the chemical formula (1)) preferablycomprises at least two types of diamine components to provide astructure of the chemical formula (2), one of which is4,4′-diaminobenzanilide. When the diamine component to provide A₁ in thechemical formula (1) comprises at least two types of diamine componentsto provide a structure of the chemical formula (2), one of which is4,4′-diaminobenzanilide, a polyimide having high heat resistance inaddition to high transparency and low linear thermal expansibility maybe obtained.

In the polyimide precursor (A-1) of the first invention, the diaminecomponent to provide A₁ in the chemical formula (1) (diamine componentto provide a repeating unit of the chemical formula (1)) particularlypreferably comprises at least one selected from2,2′-bis(trifluoromethyl)benzidine and p-phenylenediamine, and4,4′-diaminobenzanilide. When these diamine components are combinedtogether, a polyimide having high transparency and low linear thermalexpansibility, and high heat resistance may be obtained.

The diamine component to provide A₁ in the chemical formula (1) (diaminecomponent to provide a repeating unit of the chemical formula (1))preferably comprises 4,4′-diaminobenzanilide in an amount of 30 mol % ormore and 70 mol % or less, and either one or both of p-phenylenediamineand 2,2′-bis(trifluoromethyl)benzidine in an amount of 30 mol % or moreand 70 mol % or less, and particularly preferably comprises4,4′-diaminobenzanilide in an amount of 40 mol % or more and 60 mol % orless, and either one or both of p-phenylenediamine and2,2′-bis(trifluoromethyl)benzidine in an amount of 40 mol % or more and60 mol % or less. When the diamine component to provide A₁ in thechemical formula (1) comprises 4,4′-diaminobenzanilide in an amount of30 mol % or more and 70 mol % or less, and either one or both ofp-phenylenediamine and 2,2′-bis(trifluoromethyl)benzidine in an amountof 30 mol % or more and 70 mol % or less, a polyimide having hightransparency and low linear thermal expansibility, and high heatresistance may be obtained. In one embodiment, the diamine component toprovide A₁ in the chemical formula (1) (diamine component to provide arepeating unit of the chemical formula (1)) more preferably comprises4,4′-diaminobenzanilide in an amount of less than 60 mol %, morepreferably not more than 50 mol %, particularly preferably not more than40 mol %. Additionally, in one embodiment, the diamine component toprovide A₁ in the chemical formula (1) (diamine component to provide arepeating unit of the chemical formula (1)) may also preferably comprise4,4′-diaminobenzanilide in an amount of 20 mol % or more and 80 mol % orless, and either one or both of p-phenylenediamine and2,2′-bis(trifluoromethyl)benzidine in an amount of 20 mol % or more and80 mol % or less.

The polyimide precursor (A-1) of the first invention may comprise otherrepeating units other than the repeating unit represented by thechemical formula (1). Other aromatic or aliphatic tetracarboxylic acids,or the like may be used as the tetracarboxylic acid component to providethe other repeating unit. Examples thereof include derivatives of, anddianhydrides of 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane,4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylicacid, pyromellitic acid, 3,3′,4,4′-benzophenone tetracarboxylic acid,3,3′,4,4′-biphenyl tetracarboxylic acid, 2,3,3′,4′-biphenyltetracarboxylic acid, 4,4′-oxydiphthalic acid,bis(3,4-dicarboxyphenyl)sulfone dianhydride,m-terphenyl-3,4,3′,4′-tetracarboxylic dianhydride,p-terphenyl-3,4,3′,4′-tetracarboxylic dianhydride, biscarboxyphenyldimethylsilane, bis dicarboxy phenoxy diphenyl sulfide, sulfonyldiphthalic acid, 1,2,3,4-cyclobutane tetracarboxylic acid,isopropylidene diphenoxy bis phthalic acid,cyclohexane-1,2,4,5-tetracarboxylic acid,[1,1′-bi(cyclohexane)]-3,3′,4,4′-tetracarboxylic acid,[1,1′-bi(cyclohexane)]-2,3,3′,4′-tetracarboxylic acid,[1,1′-bi(cyclohexane)]-2,2′,3,3′-tetracarboxylic acid, 4,4′-methylenebis(cyclohexane-1,2-dicarboxylic acid),4,4′-(propane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic acid), 4,4′-oxybis(cyclohexane-1,2-dicarboxylic acid), 4,4′-thiobis(cyclohexane-1,2-dicarboxylic acid), 4,4′-sulfonylbis(cyclohexane-1,2-dicarboxylic acid),4,4′-(dimethylsilanediyl)bis(cyclohexane-1,2-dicarboxylic acid),4,4′-(tetrafluoropropane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylicacid), octahydropentalene-1,3,4,6-tetracarboxylic acid,bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid,6-(carboxymethyl)bicyclo[2.2.1]heptane-2,3,5-tricarboxylic acid,bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid,bicyclo[2.2.2]octa-5-ene-2,3,7,8-tetracarboxylic acid,tricyclo[4.2.2.02,5]decane-3,4,7,8-tetracarboxylic acid,tricyclo[4.2.2.02,5]deca-7-ene-3,4,9,10-tetracarboxylic acid,9-oxatricyclo[4.2.1.02,5]nonane-3,4,7,8-tetracarboxylic acid,(4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2c,3c,6c,7c-tetracarboxylic acid, and(4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2t,3t,6c,7c-tetracarboxylicacid, and the like. These may be used alone or in combination of aplurality of types. Among them, derivatives and dianhydrides ofbicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid,bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid,(4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2c,3c,6c,7c-tetracarboxylic acid, and(4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2t,3t,6c,7c-tetracarboxylic acid, and the like are more preferred, because thepolyimide is easily produced, and the obtained polyimide has excellentheat resistance. These dianhydrides may be used alone or in combinationof a plurality of types.

Additionally, five types of stereoisomers ofnorbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like (for example,norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicdianhydride) other thantrans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like, for example,cis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like may also be used as the tetracarboxylic acid componentto provide the other repeating unit.

In the polyimide precursor (A-1) of the first invention, the diaminecomponent to provide the other repeating unit other than the repeatingunit represented by the chemical formula (1) may be any one of thediamine components to provide a structure of the chemical formula (2).In other words, the aromatic diamines described as the diamine componentto provide a repeating unit of the chemical formula (1) in which A₁ is astructure of the chemical formula (2) may be used as the diaminecomponent to provide the other repeating unit other than the repeatingunit represented by the chemical formula (1). These diamines may be usedalone or in combination of a plurality of types.

In the polyimide precursor (A-1) of the first invention, other aromaticor aliphatic diamines may be used as the diamine component to providethe other repeating unit other than the repeating unit represented bythe chemical formula (1). Examples thereof include 4,4′-oxydianiline,3,4′-oxydianiline, 3,3′-oxydianiline, bis(4-aminophenyl)sulfide,p-methylene bis(phenylenediamine), 1,3-bis(4-aminophenoxy)benzene,1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene,2,2-bis[4-(4-aminophenoxyl)phenyl]hexafluoropropane,2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone,3,3-bis((aminophenoxy)phenyl)propane,2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane,bis(4-(4-aminophenoxyl)diphenyl)sulfone,bis(4-(3-aminophenoxyl)diphenyl)sulfone, octafluorobenzidine,3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diaminobiphenyl,3,3′-difluoro-4,4′-diaminobiphenyl, 9,9-bis(4-aminophenyl)fluorene,4,4′-bis(4-aminophenoxy)biphenyl, 4,4′-bis(3-aminophenoxy)biphenyl,1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane,1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane,1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane,1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane,1,4-diamino-2-tert-butylcyclohexane, 1,2-diaminocyclohexane, and1,4-diaminocyclohexane, and derivatives thereof. These may be used aloneor in combination of a plurality of types.

The polyimide precursor (A-2) of the second invention is a polyimideprecursor comprising at least one repeating unit represented by thechemical formula (3). The chemical formula (3), however, indicates thatin two norbornane rings (bicyclo[2.2.1]heptane), the acid group ineither 5-position or 6-position reacts with an amino group to form anamide bond (—CONH—) and the other is a group represented by the formula:—COOX₂ or a group represented by the formula: —COOY₂, both of which donot form an amide bond. The chemical formula (3) includes all of thefour structural isomers, that is,

(i) the one having a group represented by the formula: —COOX₂ in the5-position and a group represented by the formula: —CONH— in the6-position, and having a group represented by the formula: —COOY₂ in the5″-position and a group represented by the formula: —CONH-A₂- in the6″-position;

(ii) the one having a group represented by the formula: —COOX₂ in the6-position and a group represented by the formula: —CONH— in the5-position, and having a group represented by the formula: —COOY₂ in the5″-position and a group represented by the formula: —CONH-A₂- in the6″-position;

(iii) the one having a group represented by the formula: —COOX₂ in the5-position and a group represented by the formula: —CONH— in the6-position, and having a group represented by the formula: —COOY₂ in the6″-position and a group represented by the formula: —CONH-A₂- in the5″-position; and

(iv) the one having a group represented by the formula: —COOX₂ in the6-position and a group represented by the formula: —CONH— in the5-position, and having a group represented by the formula: —COOY₂ in the6″-position and a group represented by the formula: —CONH-A₂- in the5″-position. In other words, the polyimide precursor (A-2) of thepresent invention is a polyimide precursor obtained from

a tetracarboxylic acid component comprisingcis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like and

a diamine component comprising an aromatic diamine or an aliphaticdiamine, preferably an aromatic diamine.

As the tetracarboxylic acid component to provide a repeating unit of thechemical formula (3),cis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like may be used alone or in combination of a plurality oftypes.

As for the polyimide precursor (A-2) of the second invention, the totalcontent of the repeating units represented by the chemical formula (3)is 30 mol % or more based on the total repeating units. In other words,the polyimide precursor (A-2) of the second invention preferablycomprises one or more repeating units represented by the chemicalformula (3) in an amount of 30 mol % or more, more preferably 32 mol %or more, more preferably 35 mol % or more, particularly preferably 37mol % or more, in total based on the total repeating units.

As the diamine component to provide a repeating unit of the chemicalformula (3), aromatic diamines which provide the one in which A₂ is agroup represented by the chemical formula (4), and other aromatic oraliphatic diamines other than these diamines may be used.

The diamine component to provide a repeating unit of the chemicalformula (3) in which A₂ is a structure of the chemical formula (4) hasan aromatic ring, and when the diamine component has a plurality ofaromatic rings, the aromatic rings are each independently linked to eachother by direct bond, amide bond, or ester bond. When the aromatic ringsare linked at the 4-position relative to the amino group or the linkinggroup between the aromatic rings, the obtained polyimide has a linearstructure and may have low linear thermal expansibility, although thelinking position of the aromatic rings is not limited thereto.Meanwhile, the aromatic ring may be substituted by methyl ortrifluoromethyl. The substitution position is not particularly limited.

Examples of the diamine component to provide a repeating unit of thechemical formula (3) in which A₂ is a structure of the chemical formula(4) include, but not limited to, p-phenylenediamine, m-phenylenediamine,benzidine, 3,3′-diamino-biphenyl, 2,2′-bis(trifluoromethyl)benzidine,3,3′-bis(trifluoromethyl)benzidine, m-tolidine, 4,4′-diaminobenzanilide,3,4′-diaminobenzanilide, N,N′-bis(4-aminophenyl)terephthalamide,N,N′-p-phenylene bis(p-aminobenzamide),4-aminophenoxy-4-diaminobenzoate, bis(4-aminophenyl)terephthalate,biphenyl-4,4′-dicarboxylic acid bis(4-aminophenyl)ester, p-phenylenebis(p-aminobenzoate),bis(4-aminophenyl)-[1,1′-biphenyl]-4,4′-dicarboxylate, and[1,1′-biphenyl]-4,4′-diyl bis(4-aminobenzoate). The diamine componentmay be used alone or in combination of a plurality of types. Among them,p-phenylenediamine, m-tolidine, 4,4′-diaminobenzanilide,4-aminophenoxy-4-diaminobenzoate, 2,2′-bis(trifluoromethyl)benzidine,benzidine, N,N′-bis(4-aminophenyl)terephthalamide, andbiphenyl-4,4′-dicarboxylic acid bis(4-aminophenyl)ester are preferred,and p-phenylenediamine, 4,4′-diaminobenzanilide, and2,2′-bis(trifluoromethyl)benzidine are more preferred. Whenp-phenylenediamine, 4,4′-diaminobenzanilide, or2,2′-bis(trifluoromethyl)benzidine is used as the diamine component, theobtained polyimide may combine high heat resistance and high lighttransmittance. These diamines may be used alone or in combination of aplurality of types. In one embodiment, the one in which the diaminecomponent is only 4,4′-diaminobenzanilide singly may be excluded. In oneembodiment, the one in which the diamine component is a combination of4,4′-diaminobenzanilide and a diamine component which provides arepeating unit of the chemical formula (3) in which A₂ is a structureother than the chemical formula (4) (other diamines other than thediamine component which provides the one in which A₂ is a structure ofthe chemical formula (4)) may be excluded. Meanwhile, o-tolidine is notpreferred because it is highly hazardous.

As the diamine component to provide a repeating unit of the chemicalformula (3), other diamines other than the diamine component whichprovides the one in which A₂ is a structure of the chemical formula (4)may be used in combination therewith. As the other diamine component,other aromatic or aliphatic diamines may be used. Examples of the otherdiamine component include 4,4′-oxydianiline, 3,4′-oxydianiline,3,3′-oxydianiline, bis(4-aminophenyl)sulfide, p-methylenebis(phenylenediamine), 1,3-bis(4-aminophenoxy)benzene,1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene,2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane,2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone,3,3-bis((aminophenoxy)phenyl)propane,2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane,bis(4-(4-aminophenoxyl)diphenyl)sulfone,bis(4-(3-aminophenoxyl)diphenyl)sulfone, octafluorobenzidine,3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diaminobiphenyl,3,3′-difluoro-4,4′-diaminobiphenyl, 9,9-bis(4-aminophenyl)fluorene,4,4′-bis(4-aminophenoxy)biphenyl, 4,4′-bis(3-aminophenoxy)biphenyl,1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane,1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane,1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane,1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane,1,4-diamino-2-tert-butylcyclohexane, 1,2-diaminocyclohexane, and1,4-diaminocyclohexane, and derivatives thereof. These may be used aloneor in combination of a plurality of types.

The polyimide precursor (A-2) of the second invention preferablycomprises at least one repeating unit of the chemical formula (3) inwhich A₂ is a group represented by the chemical formula (4). In otherwords, the diamine component to provide a repeating unit of the chemicalformula (3) preferably comprises a diamine component to provide arepeating unit of the chemical formula (3) in which A₂ is a structure ofthe chemical formula (4). When the diamine component to provide A₂ inthe chemical formula (3) is a diamine component to provide a structureof the chemical formula (4), the heat resistance of the obtainedpolyimide may be improved.

As for the polyimide precursor (A-2) of the second invention, the ratioof the diamine component to provide a structure of the chemical formula(4) may be preferably 50 mol % or more, more preferably 70 mol % ormore, more preferably 80 mol % or more, further preferably 90 mol % ormore, particularly preferably 100 mol %, in total based on 100 mol % ofthe diamine component to provide A₂ in the chemical formula (3). Inother words, the ratio of one or more repeating units of the chemicalformula (3) in which A₂ is a structure of the chemical formula (4) ispreferably 50 mol % or more, more preferably 70 mol % or more, morepreferably 80 mol % or more, further preferably 90 mol % or more,particularly preferably 100 mol %, in total based on the total repeatingunits represented by the chemical formula (3). When the ratio of thediamine component to provide a structure of the chemical formula (4) isless than 50 mol %, the coefficient of linear thermal expansion of theobtained polyimide may be greater. In one embodiment, in view of themechanical properties of the obtained polyimide, the ratio of thediamine component to provide a structure of the chemical formula (4) maybe preferably 80 mol % or less, more preferably 90 mol % or less, orless than 90 mol %, in total based on 100 mol % of the diamine componentto provide A₂ in the chemical formula (3). For example, other aromaticor aliphatic diamines such as 4,4′-oxydianiline may be used preferablyin an amount of less than 20 mol %, more preferably not more than 10 mol%, more preferably less than 10 mol %, based on 100 mol % of the diaminecomponent to provide a repeating unit of the chemical formula (3).

The polyimide precursor (A-2) of the second invention preferablycomprises at least two types of repeating units of the chemical formula(3) in which A₂ is a group represented by the chemical formula (4). Inother words, the diamine component to provide a repeating unit of thechemical formula (3) preferably comprises at least two types of diaminecomponents to provide a repeating unit of the chemical formula (3) inwhich A₂ is a structure of the chemical formula (4). When the diaminecomponent to provide A₂ in the chemical formula (3) comprises at leasttwo types of diamine components to provide a structure of the chemicalformula (4), the balance between high transparency and low linearthermal expansibility of the obtained polyimide may be achieved (thatis, a polyimide having high transparency and low coefficient of linearthermal expansion may be obtained).

The polyimide precursor (A-2) of the second invention more preferablycomprises

(i) at least one type of repeating unit (3-1) of the chemical formula(3) in which A₂ is a structure of the chemical formula (4) in which m₂and/or n₂ is 1 to 3; and Z₂ and/or W₂ each independently is —NHCO—,—CONH—, —COO— or —OCO—, and

(ii) at least one type of repeating unit (3-2) of the chemical formula(3) in which A₂ is a structure of the chemical formula (4) in which m₂and n₂ are 0, or a structure of the chemical formula (4) in which m₂and/or n₂ is 1 to 3; and Z₂ and W₂ are direct bond.

As the repeating unit (3-1), a repeating unit of the chemical formula(3) in which A₂ is a group represented by any one of the chemicalformulas (D-1) to (D-3) is preferred, and a repeating unit of thechemical formula (3) in which A₂ is a group represented by any one ofthe chemical formulas (D-1) to (D-2) is more preferred. The diaminecomponent to provide a repeating unit of the chemical formula (3) inwhich A₂ is a group represented by the chemical formula (D-1) or thechemical formula (D-2) is 4,4′-diaminobenzanilide, and the diaminecomponent to provide a repeating unit of the chemical formula (3) inwhich A₂ is a group represented by the chemical formula (D-3) isbis(4-aminophenyl)terephthalate. These diamines may be used alone or incombination of a plurality of types.

As the repeating unit (3-2), a repeating unit of the chemical formula(3) in which A₂ is a group represented by any one of the chemicalformulas (D-4) to (D-6) is preferred, and a repeating unit of thechemical formula (3) in which A₂ is a group represented by any one ofthe chemical formulas (D-4) to (D-5) is more preferred. The diaminecomponent to provide a repeating unit of the chemical formula (3) inwhich A₂ is a group represented by the chemical formula (D-4) isp-phenylenediamine, and the diamine component to provide a repeatingunit of the chemical formula (3) in which A₂ is a group represented bythe chemical formula (D-5) is 2,2′-bis(trifluoromethyl)benzidine, andthe diamine component to provide a repeating unit of the chemicalformula (3) in which A₂ is a group represented by the chemical formula(D-6) is m-tolidine. These diamines may be used alone or in combinationof a plurality of types.

It is preferred that, in the polyimide precursor (A-2) of the secondinvention, the ratio of one or more repeating units (3-1) is 30 mol % ormore and 70 mol % or less in total based on the total repeating unitsrepresented by the chemical formula (3), and the ratio of one or morerepeating units (3-2) is 30 mol % or more and 70 mol % or less in totalbased on the total repeating units represented by the chemical formula(3). It is particularly preferred that the ratio of one or morerepeating units (3-1) is 40 mol % or more and 60 mol % or less in totalbased on the total repeating units represented by the chemical formula(3), and the ratio of one or more repeating units (3-2) is 40 mol % ormore and 60 mol % or less in total based on the total repeating unitsrepresented by the chemical formula (3). In one embodiment, the ratio ofthe repeating unit (3-1) is more preferably less than 60 mol %, morepreferably not more than 50 mol %, particularly preferably not more than40 mol %, in total based on the total repeating units represented by thechemical formula (3).

Additionally, in one embodiment, the polyimide precursor may preferablycomprise other repeating units represented by the chemical formula (3)other than the repeating unit (3-1) and the repeating unit (3-2) (forexample, the one in which A₂ has a plurality of aromatic rings and thearomatic rings are linked to each other by ether bond (—O—)) preferablyin an amount of less than 20 mol %, more preferably not more than 10 mol%, particularly preferably less than 10 mol %, based on the totalrepeating units represented by the chemical formula (3). Additionally,in one embodiment, it may be also preferred that the ratio of one ormore repeating units (3-1) is 20 mol % or more and 80 mol % or less intotal based on the total repeating units represented by the chemicalformula (3), and the ratio of one or more repeating units (3-2) is 20mol % or more and 80 mol % or less in total based on the total repeatingunits represented by the chemical formula (3).

In the polyimide precursor (A-2) of the second invention, the diaminecomponent to provide A₂ in the chemical formula (3) (diamine componentto provide a repeating unit of the chemical formula (3)) preferablycomprises at least two types of diamine components to provide astructure of the chemical formula (4), one of which is4,4′-diaminobenzanilide. When the diamine component to provide A₂ in thechemical formula (3) comprises at least two types of diamine componentsto provide a structure of the chemical formula (4), one of which is4,4′-diaminobenzanilide, a polyimide having high heat resistance inaddition to high transparency and low linear thermal expansibility maybe obtained.

In the polyimide precursor (A-2) of the second invention, the diaminecomponent to provide A₂ in the chemical formula (3) (diamine componentto provide a repeating unit of the chemical formula (3)) particularlypreferably comprises at least one selected from2,2′-bis(trifluoromethyl)benzidine and p-phenylenediamine, and4,4′-diaminobenzanilide. When these diamine components are combinedtogether, a polyimide having high transparency and low linear thermalexpansibility, and high heat resistance may be obtained.

The diamine component to provide A₂ in the chemical formula (3) (diaminecomponent to provide a repeating unit of the chemical formula (3))preferably comprises 4,4′-diaminobenzanilide in an amount of 30 mol % ormore and 70 mol % or less, and either one or both of p-phenylenediamineand 2,2′-bis(trifluoromethyl)benzidine in an amount of 30 mol % or moreand 70 mol % or less, and particularly preferably comprises4,4′-diaminobenzanilide in an amount of 40 mol % or more and 60 mol % orless, and either one or both of p-phenylenediamine and2,2′-bis(trifluoromethyl)benzidine in an amount of 40 mol % or more and60 mol % or less. When the diamine component to provide A₂ in thechemical formula (3) comprises 4,4′-diaminobenzanilide in an amount of30 mol % or more and 70 mol % or less, and either one or both ofp-phenylenediamine and 2,2′-bis(trifluoromethyl)benzidine in an amountof 30 mol % or more and 70 mol % or less, a polyimide having hightransparency and low linear thermal expansibility, and high heatresistance may be obtained. In one embodiment, the diamine component toprovide A₂ in the chemical formula (3) (diamine component to provide arepeating unit of the chemical formula (3)) more preferably comprises4,4′-diaminobenzanilide in an amount of less than 60 mol %, morepreferably not more than 50 mol %, particularly preferably not more than40 mol %. Additionally, in one embodiment, the diamine component toprovide A₂ in the chemical formula (3) (diamine component to provide arepeating unit of the chemical formula (3)) may also preferably comprise4,4′-diaminobenzanilide in an amount of 20 mol % or more and 80 mol % orless, and either one or both of p-phenylenediamine and2,2′-bis(trifluoromethyl)benzidine in an amount of 20 mol % or more and80 mol % or less.

The polyimide precursor (A-2) of the second invention may comprise otherrepeating units other than the repeating unit represented by thechemical formula (3). Other aromatic or aliphatic tetracarboxylic acids,or the like may be used as the tetracarboxylic acid component to providethe other repeating unit. Examples thereof include derivatives of, anddianhydrides of 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane,4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylicacid, pyromellitic acid, 3,3′,4,4′-benzophenone tetracarboxylic acid,3,3′,4,4′-biphenyl tetracarboxylic acid, 2,3,3′,4′-biphenyltetracarboxylic acid, 4,4′-oxydiphthalic acid,bis(3,4-dicarboxyphenyl)sulfone dianhydride,m-terphenyl-3,4,3′,4′-tetracarboxylic dianhydride,p-terphenyl-3,4,3′,4′-tetracarboxylic dianhydride, biscarboxyphenyldimethylsilane, bis dicarboxy phenoxy diphenyl sulfide, sulfonyldiphthalic acid, 1,2,3,4-cyclobutane tetracarboxylic acid,isopropylidene diphenoxy bis phthalic acid,cyclohexane-1,2,4,5-tetracarboxylic acid,[1,1′-bi(cyclohexane)]-3,3′,4,4′-tetracarboxylic acid,[1,1′-bi(cyclohexane)]-2,3,3′,4′-tetracarboxylic acid,[1,1′-bi(cyclohexane)]-2,2′,3,3′-tetracarboxylic acid, 4,4′-methylenebis(cyclohexane-1,2-dicarboxylic acid),4,4′-(propane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic acid), 4,4′-oxybis(cyclohexane-1,2-dicarboxylic acid), 4,4′-thiobis(cyclohexane-1,2-dicarboxylic acid), 4,4′-sulfonylbis(cyclohexane-1,2-dicarboxylic acid),4,4′-(dimethylsilanediyl)bis(cyclohexane-1,2-dicarboxylic acid),4,4′-(tetrafluoropropane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylicacid), octahydropentalene-1,3,4,6-tetracarboxylic acid,bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid,6-(carboxymethyl)bicyclo[2.2.1]heptane-2,3,5-tricarboxylic acid,bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid,bicyclo[2.2.2]octa-5-ene-2,3,7,8-tetracarboxylic acid,tricyclo[4.2.2.02,5]decane-3,4,7,8-tetracarboxylic acid,tricyclo[4.2.2.02,5]deca-7-ene-3,4,9,10-tetracarboxylic acid,9-oxatricyclo[4.2.1.02,5]nonane-3,4,7,8-tetracarboxylic acid,(4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2c,3c,6c,7c-tetracarboxylicacid, and(4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2t,3t,6c,7c-tetracarboxylicacid, and the like. These may be used alone or in combination of aplurality of types. Among them, derivatives and dianhydrides ofbicyclo[2.2.]heptane-2,3,5,6-tetracarboxylic acid,bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid, (4arH,8acH)-decahydro-1t, 4t:5c,8c-dimethanonaphthalene-2c, 3c,6c,7c-tetracarboxylic acid, and (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2t,3t,6c,7c-tetracarboxylic acid, and the likeare more preferred, because the polyimide is easily produced, and theobtained polyimide has excellent heat resistance. These dianhydrides maybe used alone or in combination of a plurality of types.

Additionally, five types of stereoisomers ofnorbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like (for example,norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicdianhydride) other thancis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like, for example,trans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like may also be used as the tetracarboxylic acid componentto provide the other repeating unit.

In the polyimide precursor (A-2) of the second invention, the diaminecomponent to provide the other repeating unit other than the repeatingunit represented by the chemical formula (3) may be any one of thediamine components to provide a structure of the chemical formula (4).In other words, the aromatic diamines described as the diamine componentto provide a repeating unit of the chemical formula (3) in which A₂ is astructure of the chemical formula (4) may be used as the diaminecomponent to provide the other repeating unit other than the repeatingunit represented by the chemical formula (3). These diamines may be usedalone or in combination of a plurality of types.

In the polyimide precursor (A-2) of the second invention, other aromaticor aliphatic diamines may be used as the diamine component to providethe other repeating unit other than the repeating unit represented bythe chemical formula (3). Examples thereof include 4,4′-oxydianiline,3,4′-oxydianiline, 3,3′-oxydianiline, bis(4-aminophenyl)sulfide,p-methylene bis(phenylenediamine), 1,3-bis(4-aminophenoxy)benzene,1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene,2,2-bis[4-(4-aminophenoxyl)phenyl]hexafluoropropane,2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone,3,3-bis((aminophenoxy)phenyl)propane,2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane,bis(4-(4-aminophenoxyl)diphenyl)sulfone,bis(4-(3-aminophenoxyl)diphenyl)sulfone, octafluorobenzidine,3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diaminobiphenyl,3,3′-difluoro-4,4′-diaminobiphenyl, 9,9-bis(4-aminophenyl)fluorene,4,4′-bis(4-aminophenoxy)biphenyl, 4,4′-bis(3-aminophenoxy)biphenyl,1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane,1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane,1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane,1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane,1,4-diamino-2-tert-butylcyclohexane, 1,2-diaminocyclohexane, and1,4-diaminocyclohexane, and derivatives thereof. These may be used aloneor in combination of a plurality of types.

The polyimide precursor (A-3) of the third invention is a polyimideprecursor comprising at least one of repeating units represented by thechemical formula (5) and the chemical formula (6). The chemical formula(5), however, indicates that in two norbornane rings(bicyclo[2.2.1]heptane), the acid group in either 5-position or6-position reacts with an amino group to form an amide bond (—CONH—) andthe other is a group represented by the formula: —COOX₃ or a grouprepresented by the formula: —COOY₃, both of which do not form an amidebond. The chemical formula (5) includes all of the four structuralisomers, that is,

(i) the one having a group represented by the formula: —COOX₃ in the5-position and a group represented by the formula: —CONH— in the6-position, and having a group represented by the formula: —COOY₃ in the5″-position and a group represented by the formula: —CONH-A₃- in the6″-position;

(ii) the one having a group represented by the formula: —COOX₃ in the6-position and a group represented by the formula: —CONH— in the5-position, and having a group represented by the formula: —COOY₃ in the5″-position and a group represented by the formula: —CONH-A₃- in the6″-position;

(iii) the one having a group represented by the formula: —COOX₃ in the5-position and a group represented by the formula: —CONH— in the6-position, and having a group represented by the formula: —COOY₃ in the6″-position and a group represented by the formula: —CONH-A₃- in the5″-position; and

(iv) the one having a group represented by the formula: —COOX₃ in the6-position and a group represented by the formula: —CONH— in the5-position, and having a group represented by the formula: —COOY₃ in the6″-position and a group represented by the formula: —CONH-A₃- in the5″-position. The chemical formula (6) indicates that in two norbornanerings (bicyclo[2.2.1]heptane), the acid group in either 5-position or6-position reacts with an amino group to form an amide bond (—CONH—) andthe other is a group represented by the formula: —COOX₄ or a grouprepresented by the formula: —COOY₄, both of which do not form an amidebond. The chemical formula (6) includes all of the four structuralisomers, that is,

(i) the one having a group represented by the formula: —COOX₄ in the5-position and a group represented by the formula: —CONH— in the6-position, and having a group represented by the formula: —COOY₄ in the5″-position and a group represented by the formula: —CONH-A₃- in the6″-position;

(ii) the one having a group represented by the formula: —COOX₄ in the6-position and a group represented by the formula: —CONH— in the5-position, and having a group represented by the formula: —COOY₄ in the5″-position and a group represented by the formula: —CONH-A₃- in the6″-position;

(iii) the one having a group represented by the formula: —COOX₄ in the5-position and a group represented by the formula: —CONH— in the6-position, and having a group represented by the formula: —COOY₄ in the6″-position and a group represented by the formula: —CONH-A₃- in the5″-position; and

(iv) the one having a group represented by the formula: —COOX₄ in the6-position and a group represented by the formula: —CONH— in the5-position, and having a group represented by the formula: —COOY₄ in the6″-position and a group represented by the formula: —CONH-A₃- in the5″-position. In other words, the polyimide precursor (A-3) of thepresent invention is a polyimide precursor obtained from

a tetracarboxylic acid component comprising at least one oftrans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like and/or at least one ofcis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like and

a diamine component comprising an aromatic diamine or an aliphaticdiamine, preferably an aromatic diamine.

As the tetracarboxylic acid component to provide a repeating unit of thechemical formula (5),trans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like may be used alone or in combination of a plurality oftypes. As the tetracarboxylic acid component to provide a repeating unitof the chemical formula (6),cis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like may be used alone or in combination of a plurality oftypes. As for the polyimide precursor (A-3) of the third invention, onlyone or more of the tetracarboxylic acid component to provide a repeatingunit of the chemical formula (5)(trans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like) may be used, or alternatively, only one or more ofthe tetracarboxylic acid component to provide a repeating unit of thechemical formula (6)(cis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like) may be used, or alternatively, both one or more ofthe tetracarboxylic acid component to provide a repeating unit of thechemical formula (5)(trans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like) and one or more of the tetracarboxylic acid componentto provide a repeating unit of the chemical formula (6)(cis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like) may be used.

As for the polyimide precursor (A-3) of the third invention, the totalcontent of the repeating units represented by the chemical formula (5)and the chemical formula (6) is 80 mol % or more based on the totalrepeating units. In other words, the polyimide precursor (A-3) of thethird invention comprises at least one of repeating units represented bythe chemical formula (5) and the chemical formula (6), and preferablycomprises the repeating units in an amount of 80 mol % or more, morepreferably 90 mol % or more, more preferably 95 mol % or more,particularly preferably 99 mol % or more, in total based on the totalrepeating units. When the polyimide precursor comprises at least one ofrepeating units represented by the chemical formula (5) and the chemicalformula (6), and preferably comprises the repeating units in an amountof 80 mol % or more in total based on the total repeating units, theobtained polyimide has a lower coefficient of linear thermal expansion.

The polyimide precursor (A-3) of the third invention preferablycomprises one or more of the repeating unit represented by the chemicalformula (5) and one or more of the repeating unit represented by thechemical formula (6), and preferably comprises one or more of therepeating unit represented by the chemical formula (5) preferably in anamount of 50 mol % or more in total based on the total repeating unitsand one or more of the repeating unit represented by the chemicalformula (6) preferably in an amount of 30 mol % or more in total basedon the total repeating units. In other words, it is preferred that thetotal content of the repeating units represented by the chemical formula(5) is 50 mol % or more based on the total repeating units and the totalcontent of the repeating units represented by the chemical formula (6)is 30 mol % or more based on the total repeating units. When thepolyimide precursor comprises one or more of the repeating unitrepresented by the chemical formula (5) in an amount of 50 mol % or morebased on the total repeating units and one or more of the repeating unitrepresented by the chemical formula (6) in an amount of 30 mol % or morebased on the total repeating units, the obtained polyimide has a lowercoefficient of linear thermal expansion.

As the diamine component to provide a repeating unit of the chemicalformula (5) and the diamine component to provide a repeating unit of thechemical formula (6), aromatic diamines which provide the one in whichA₃ is a group represented by the chemical formula (7), and otheraromatic or aliphatic diamines other than these diamines may be used.

The diamine component to provide repeating units of the chemical formula(5) and the chemical formula (6) in which A₃ is a structure of thechemical formula (7) has an aromatic ring, and when the diaminecomponent has a plurality of aromatic rings, the aromatic rings are eachindependently linked to each other by direct bond, amide bond, or esterbond. When the aromatic rings are linked at the 4-position relative tothe amino group or the linking group between the aromatic rings, theobtained polyimide has a linear structure and may have low linearthermal expansibility, although the linking position of the aromaticrings is not limited thereto. Meanwhile, the aromatic ring may besubstituted by methyl or trifluoromethyl. The substitution position isnot particularly limited.

Examples of the diamine component to provide repeating units of thechemical formula (5) and the chemical formula (6) in which A₃ is astructure of the chemical formula (7) include, but not limited to,p-phenylenediamine, m-phenylenediamine, benzidine,3,3′-diamino-biphenyl, 2,2′-bis(trifluoromethyl)benzidine,3,3′-bis(trifluoromethyl)benzidine, m-tolidine, 4,4′-diaminobenzanilide,3,4′-diaminobenzanilide, N,N′-bis(4-aminophenyl)terephthalamide,N,N′-p-phenylene bis(p-aminobenzamide),4-aminophenoxy-4-diaminobenzoate, bis(4-aminophenyl)terephthalate,biphenyl-4,4′-dicarboxylic acid bis(4-aminophenyl)ester, p-phenylenebis(p-aminobenzoate),bis(4-aminophenyl)-[1,1′-biphenyl]-4,4′-dicarboxylate, and[1,1′-biphenyl]-4,4′-diyl bis(4-aminobenzoate). The diamine componentmay be used alone or in combination of a plurality of types. Among them,p-phenylenediamine, m-tolidine, 4,4′-diaminobenzanilide,4-aminophenoxy-4-diaminobenzoate, 2,2′-bis(trifluoromethyl)benzidine,benzidine, N,N′-bis(4-aminophenyl)terephthalamide, andbiphenyl-4,4′-dicarboxylic acid bis(4-aminophenyl)ester are preferred,and p-phenylenediamine, 4,4′-diaminobenzanilide, and2,2′-bis(trifluoromethyl)benzidine are more preferred. Whenp-phenylenediamine, 4,4′-diaminobenzanilide, or2,2′-bis(trifluoromethyl)benzidine is used as the diamine component, theobtained polyimide may combine high heat resistance and high lighttransmittance. These diamines may be used alone or in combination of aplurality of types. In one embodiment, the one in which the diaminecomponent is only 4,4′-diaminobenzanilide singly may be excluded. In oneembodiment, the one in which the diamine component is a combination of4,4′-diaminobenzanilide and a diamine component which provides repeatingunits of the chemical formula (5) and the chemical formula (6) in whichA₃ is a structure other than the chemical formula (7) (other diaminesother than the diamine component which provides the one in which A₃ is astructure of the chemical formula (7)) may be excluded. Meanwhile,o-tolidine is not preferred because it is highly hazardous.

As the diamine component to provide a repeating unit of the chemicalformula (5) and a repeating unit of the chemical formula (6), otherdiamines other than the diamine component which provides the one inwhich A₃ is a structure of the chemical formula (7) may be used incombination therewith. As the other diamine component, other aromatic oraliphatic diamines may be used. Examples of the other diamine componentinclude 4,4′-oxydianiline, 3,4′-oxydianiline, 3,3′-oxydianiline,bis(4-aminophenyl)sulfide, p-methylene bis(phenylenediamine),1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene,1,4-bis(4-aminophenoxy)benzene,2,2-bis[4-(4-aminophenoxyl)phenyl]hexafluoropropane,2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone,3,3-bis((aminophenoxy)phenyl)propane,2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane,bis(4-(4-aminophenoxy)diphenyl)sulfone,bis(4-(3-aminophenoxyl)diphenyl)sulfone, octafluorobenzidine,3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diaminobiphenyl,3,3′-difluoro-4,4′-diaminobiphenyl, 9,9-bis(4-aminophenyl)fluorene,4,4′-bis(4-aminophenoxy)biphenyl, 4,4′-bis(3-aminophenoxy)biphenyl,1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane,1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane,1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane,1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane,1,4-diamino-2-tert-butylcyclohexane, 1,2-diaminocyclohexane, and1,4-diaminocyclohexane, and derivatives thereof. These may be used aloneor in combination of a plurality of types.

The polyimide precursor (A-3) of the third invention preferablycomprises at least one repeating unit of the chemical formula (5) inwhich A₃ is a group represented by the chemical formula (7) and/or atleast one repeating unit of the chemical formula (6) in which A₃ is agroup represented by the chemical formula (7). In other words, thediamine component to provide repeating units of the chemical formula (5)and the chemical formula (6) preferably comprises a diamine component toprovide the one in which A₃ is a structure of the chemical formula (7).When the diamine component to provide A₃ in the chemical formula (5) andthe chemical formula (6) is a diamine component to provide a structureof the chemical formula (7), the heat resistance of the obtainedpolyimide may be improved.

As for the polyimide precursor (A-3) of the third invention, the ratioof the diamine component to provide a structure of the chemical formula(7) may be preferably 50 mol % or more, more preferably 70 mol % ormore, more preferably 80 mol % or more, further preferably 90 mol % ormore, particularly preferably 100 mol %, in total based on 100 mol % ofthe diamine component to provide A₃ in the chemical formula (5) and thechemical formula (6). In other words, the ratio of one or more repeatingunits of the chemical formula (5) and the chemical formula (6) in whichA₃ is a structure of the chemical formula (7) is preferably 50 mol % ormore, more preferably 70 mol % or more, more preferably 80 mol % ormore, further preferably 90 mol % or more, particularly preferably 100mol %, in total based on the total repeating units represented by thechemical formula (5) and the chemical formula (6). When the ratio of thediamine component to provide a structure of the chemical formula (7) isless than 50 mol %, the coefficient of linear thermal expansion of theobtained polyimide may be greater. In one embodiment, in view of themechanical properties of the obtained polyimide, the ratio of thediamine component to provide a structure of the chemical formula (7) maybe preferably 80 mol % or less, more preferably 90 mol % or less, orless than 90 mol %, in total based on 100 mol % of the diamine componentto provide A₃ in the chemical formula (5) and the chemical formula (6).For example, other aromatic or aliphatic diamines such as4,4′-oxydianiline may be used preferably in an amount of less than 20mol %, more preferably not more than 10 mol %, more preferably less than10 mol %, based on 100 mol % of the diamine component to providerepeating units of the chemical formula (5) and the chemical formula(6).

The polyimide precursor (A-3) of the third invention preferablycomprises at least two types of repeating units of the chemical formula(5) or the chemical formula (6) in which A₃ is a group represented bythe chemical formula (7). In other words, the diamine component toprovide repeating units of the chemical formula (5) and the chemicalformula (6) preferably comprises at least two types of diaminecomponents to provide repeating units of the chemical formula (5) andthe chemical formula (6) in which A₃ is a structure of the chemicalformula (7). When the diamine component to provide A₃ in the chemicalformula (5) and the chemical formula (6) comprises at least two types ofdiamine components to provide a structure of the chemical formula (7),the balance between high transparency and low linear thermalexpansibility of the obtained polyimide may be achieved (that is, apolyimide having high transparency and low coefficient of linear thermalexpansion may be obtained). The polyimide precursor (A-3) of the thirdinvention may be the one comprising at least two types of repeatingunits of the chemical formula (5) in which A₃ is a structure of thechemical formula (7), or alternatively, may be the one comprising atleast two types of repeating units of the chemical formula (6) in whichA₃ is a structure of the chemical formula (7), or alternatively, may bethe one comprising at least one type of repeating unit of the chemicalformula (5) in which A₃ is a structure of the chemical formula (7) andat least one type of repeating unit of the chemical formula (6) in whichA₃ is a structure of the chemical formula (7).

The polyimide precursor (A-3) of the third invention more preferablycomprises

(i) at least one type of repeating unit (5-1) of the chemical formula(5) and the chemical formula (6) in which A₃ is a structure of thechemical formula (7) in which m₃ and/or n₃ is 1 to 3; and Z₃ and/or W₃each independently is —NHCO—, —CONH—, —COO— or —OCO—, and

(ii) at least one type of repeating unit (5-2) of the chemical formula(5) and the chemical formula (6) in which A₃ is a structure of thechemical formula (7) in which m₃ and n₃ are 0, or a structure of thechemical formula (7) in which m₃ and/or n₃ is 1 to 3; and Z₃ and W₃ aredirect bond.

As the repeating unit (5-1), repeating units of the chemical formula (5)and the chemical formula (6) in which A₃ is a group represented by anyone of the chemical formulas (D-1) to (D-3) are preferred, and repeatingunits of the chemical formula (5) and the chemical formula (6) in whichA₃ is a group represented by any one of the chemical formulas (D-1) to(D-2) are more preferred. The diamine component to provide repeatingunits of the chemical formula (5) and the chemical formula (6) in whichA₃ is a group represented by the chemical formula (D-1) or the chemicalformula (D-2) is 4,4′-diaminobenzanilide, and the diamine component toprovide repeating units of the chemical formula (5) and the chemicalformula (6) in which A₃ is a group represented by the chemical formula(D-3) is bis(4-aminophenyl)terephthalate. These diamines may be usedalone or in combination of a plurality of types.

As the repeating unit (5-2), repeating units of the chemical formula (5)and the chemical formula (6) in which A₃ is a group represented by anyone of the chemical formulas (D-4) to (D-6) are preferred, and repeatingunits of the chemical formula (5) and the chemical formula (6) in whichA₃ is a group represented by any one of the chemical formulas (D-4) to(D-5) are more preferred. The diamine component to provide repeatingunits of the chemical formula (5) and the chemical formula (6) in whichA₃ is a group represented by the chemical formula (D-4) isp-phenylenediamine, and the diamine component to provide repeating unitsof the chemical formula (5) and the chemical formula (6) in which A₃ isa group represented by the chemical formula (D-5) is2,2′-bis(trifluoromethyl)benzidine, and the diamine component to providerepeating units of the chemical formula (5) and the chemical formula (6)in which A₃ is a group represented by the chemical formula (D-6) ism-tolidine. These diamines may be used alone or in combination of aplurality of types.

It is preferred that, in the polyimide precursor (A-3) of the thirdinvention, the ratio of one or more repeating units (5-1) is 30 mol % ormore and 70 mol % or less in total based on the total repeating unitsrepresented by the chemical formula (5) and the chemical formula (6),and the ratio of one or more repeating units (5-2) is 30 mol % or moreand 70 mol % or less in total based on the total repeating unitsrepresented by the chemical formula (5) and the chemical formula (6). Itis particularly preferred that the ratio of one or more repeating units(5-1) is 40 mol % or more and 60 mol % or less in total based on thetotal repeating units represented by the chemical formula (5) and thechemical formula (6), and the ratio of one or more repeating units (5-2)is 40 mol % or more and 60 mol % or less in total based on the totalrepeating units represented by the chemical formula (5) and the chemicalformula (6). In one embodiment, the ratio of the repeating unit (5-1) ismore preferably less than 60 mol %, more preferably not more than 50 mol%, particularly preferably not more than 40 mol %, in total based on thetotal repeating units represented by the chemical formula (5) and thechemical formula (6). Additionally, in one embodiment, the polyimideprecursor may preferably comprise other repeating units represented bythe chemical formula (5) and the chemical formula (6) other than therepeating unit (5-1) and the repeating unit (5-2) (for example, the onein which A₃ has a plurality of aromatic rings and the aromatic rings arelinked to each other by ether bond (—O—)) preferably in an amount ofless than 20 mol %, more preferably not more than 10 mol %, particularlypreferably less than 10 mol %, based on the total repeating unitsrepresented by the chemical formula (5) and the chemical formula (6).Additionally, in one embodiment, it may be also preferred that the ratioof one or more repeating units (5-1) is 20 mol % or more and 80 mol % orless in total based on the total repeating units represented by thechemical formula (5) and the chemical formula (6), and the ratio of oneor more repeating units (5-2) is 20 mol % or more and 80 mol % or lessin total based on the total repeating units represented by the chemicalformula (5) and the chemical formula (6).

In the polyimide precursor (A-3) of the third invention, the diaminecomponent to provide A₃ in the chemical formula (5) and the chemicalformula (6) (diamine component to provide repeating units of thechemical formula (5) and the chemical formula (6)) preferably comprisesat least two types of diamine components to provide a structure of thechemical formula (7), one of which is 4,4′-diaminobenzanilide. When thediamine component to provide A₃ in the chemical formula (5) and thechemical formula (6) comprises at least two types of diamine componentsto provide a structure of the chemical formula (7), one of which is4,4′-diaminobenzanilide, a polyimide having high heat resistance inaddition to high transparency and low linear thermal expansibility maybe obtained.

In the polyimide precursor (A-3) of the third invention, the diaminecomponent to provide A₃ in the chemical formula (5) and the chemicalformula (6) (diamine component to provide repeating units of thechemical formula (5) and the chemical formula (6)) particularlypreferably comprises at least one selected from2,2′-bis(trifluoromethyl)benzidine and p-phenylenediamine, and4,4′-diaminobenzanilide. When these diamine components are combinedtogether, a polyimide having high transparency and low linear thermalexpansibility, and high heat resistance may be obtained.

The diamine component to provide A₃ in the chemical formula (5) and thechemical formula (6) (diamine component to provide repeating units ofthe chemical formula (5) and the chemical formula (6)) preferablycomprises 4,4′-diaminobenzanilide in an amount of 30 mol % or more and70 mol % or less, and either one or both of p-phenylenediamine and2,2′-bis(trifluoromethyl)benzidine in an amount of 30 mol % or more and70 mol % or less, and particularly preferably comprises4,4′-diaminobenzanilide in an amount of 40 mol % or more and 60 mol % orless, and either one or both of p-phenylenediamine and2,2′-bis(trifluoromethyl)benzidine in an amount of 40 mol % or more and60 mol % or less. When the diamine component to provide A₃ in thechemical formula (5) and the chemical formula (6) comprises4,4′-diaminobenzanilide in an amount of 30 mol % or more and 70 mol % orless, and either one or both of p-phenylenediamine and2,2′-bis(trifluoromethyl)benzidine in an amount of 30 mol % or more and70 mol % or less, a polyimide having high transparency and low linearthermal expansibility, and high heat resistance may be obtained. In oneembodiment, the diamine component to provide A₃ in the chemical formula(5) and the chemical formula (6) (diamine component to provide repeatingunits of the chemical formula (5) and the chemical formula (6)) morepreferably comprises 4,4′-diaminobenzanilide in an amount of less than60 mol %, more preferably not more than 50 mol %, particularlypreferably not more than 40 mol %. Additionally, in one embodiment, thediamine component to provide A₃ in the chemical formula (5) and thechemical formula (6) (diamine component to provide repeating units ofthe chemical formula (5) and the chemical formula (6)) may alsopreferably comprise 4,4′-diaminobenzanilide in an amount of 20 mol % ormore and 80 mol % or less, and either one or both of p-phenylenediamineand 2,2′-bis(trifluoromethyl)benzidine in an amount of 20 mol % or moreand 80 mol % or less.

The polyimide precursor (A-3) of the third invention may comprise otherrepeating units other than the repeating units represented by thechemical formula (5) and the chemical formula (6). Other aromatic oraliphatic tetracarboxylic acids, or the like may be used as thetetracarboxylic acid component to provide the other repeating unit.Examples thereof include derivatives of, and dianhydrides of2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane,4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylicacid, pyromellitic acid, 3,3′,4,4′-benzophenone tetracarboxylic acid,3,3′,4,4′-biphenyl tetracarboxylic acid, 2,3,3′,4′-biphenyltetracarboxylic acid, 4,4′-oxydiphthalic acid,bis(3,4-dicarboxyphenyl)sulfone dianhydride,m-terphenyl-3,4,3′,4′-tetracarboxylic dianhydride,p-terphenyl-3,4,3′,4′-tetracarboxylic dianhydride, biscarboxyphenyldimethylsilane, bis dicarboxy phenoxy diphenyl sulfide, sulfonyldiphthalic acid, 1,2,3,4-cyclobutane tetracarboxylic acid,isopropylidene diphenoxy his phthalic acid,cyclohexane-1,2,4,5-tetracarboxylic acid,[1,1′-bi(cyclohexane)]-3,3′,4,4′-tetracarboxylic acid,[1,1′-bi(cyclohexane)]-2,3,3′,4′-tetracarboxylic acid,[1,1′-bi(cyclohexane)]-2,2′,3,3′-tetracarboxylic acid, 4,4′-methylenebis(cyclohexane-1,2-dicarboxylic acid),4,4′-(propane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic acid), 4,4′-oxybis(cyclohexane-1,2-dicarboxylic acid), 4,4′-thiobis(cyclohexane-1,2-dicarboxylic acid), 4,4′-sulfonylbis(cyclohexane-1,2-dicarboxylic acid),4,4′-(dimethylsilanediyl)bis(cyclohexane-1,2-dicarboxylic acid),4,4′-(tetrafluoropropane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylicacid), octahydropentalene-1,3,4,6-tetracarboxylic acid,bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid,6-(carboxymethyl)bicyclo[2.2.1]heptane-2,3,5-tricarboxylic acid,bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid,bicyclo[2.2.2]octa-5-ene-2,3,7,8-tetracarboxylic acid,tricyclo[4.2.2.02,5]decane-3,4,7,8-tetracarboxylic acid,tricyclo[4.2.2.02,5]deca-7-ene-3,4,9,10-tetracarboxylic acid,9-oxatricyclo[4.2.1.02,5]nonane-3,4,7,8-tetracarboxylic acid,(4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2c,3c,6c,7c-tetracarboxylicacid, and(4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2t,3t,6c,7c-tetracarboxylic acid, and the like. These may be used alone or incombination of a plurality of types. Among them, derivatives anddianhydrides of bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid,bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid,(4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2c,3c,6c,7c-tetracarboxylicacid, and (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2t,3t,6c, 7c-tetracarboxylic acid, and the likeare more preferred, because the polyimide is easily produced, and theobtained polyimide has excellent heat resistance. These dianhydrides maybe used alone or in combination of a plurality of types.

Additionally, four types of stereoisomers ofnorbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like (for example,norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicdianhydride) other thancis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like, andtrans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like may also be used as the tetracarboxylic acid componentto provide the other repeating unit.

In the polyimide precursor (A-3) of the third invention, the diaminecomponent to provide the other repeating unit other than the repeatingunit represented by the chemical formula (5) and the repeating unitrepresented by the chemical formula (6) may be any one of the diaminecomponents to provide a structure of the chemical formula (7). In otherwords, the aromatic diamines described as the diamine component toprovide repeating units of the chemical formula (5) and the chemicalformula (6) in which A₃ is a structure of the chemical formula (7) maybe used as the diamine component to provide the other repeating unitother than the repeating units represented by the chemical formula (5)and the chemical formula (6). These diamines may be used alone or incombination of a plurality of types.

In the polyimide precursor (A-3) of the third invention, other aromaticor aliphatic diamines may be used as the diamine component to providethe other repeating unit other than the repeating unit represented bythe chemical formula (5) and the repeating unit represented by thechemical formula (6). Examples thereof include 4,4′-oxydianiline,3,4′-oxydianiline, 3,3′-oxydianiline, bis(4-aminophenyl)sulfide,p-methylene bis(phenylenediamine), 1,3-bis(4-aminophenoxy)benzene,1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene,2,2-bis[4-(4-aminophenoxyl)phenyl]hexafluoropropane,2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone,3,3-bis((aminophenoxy)phenyl)propane,2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane,bis(4-(4-aminophenoxy)diphenyl)sulfone,bis(4-(3-aminophenoxyl)diphenyl)sulfone, octafluorobenzidine,3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diaminobiphenyl,3,3′-difluoro-4,4′-diaminobiphenyl, 9,9-bis(4-aminophenyl)fluorene,4,4′-bis(4-aminophenoxy)biphenyl, 4,4′-bis(3-aminophenoxy)biphenyl,1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane,1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane,1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane,1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane,1,4-diamino-2-tert-butylcyclohexane, 1,2-diaminocyclohexane, and1,4-diaminocyclohexane, and derivatives thereof. These may be used aloneor in combination of a plurality of types.

The purity of the tetracarboxylic acid component to be used in thepresent invention may be preferably, but not limited to, 99% or more,more preferably 99.5% or more. (In the case where the component containsa plurality of structural isomers, the purity is determined on thecondition that the structural isomers are regarded as the same componentwithout distinguishing them. In the case where a plurality of types oftetracarboxylic acid components are used, the purity is the value of thetetracarboxylic acid component having the highest purity, or the averagevalue of the purities of all tetracarboxylic acid components to be usedwhich are determined separately and weighted with the mass ratio of theused components; for example, the purity of the tetracarboxylic acidcomponent used is calculated to be 97% when 70 parts by mass of atetracarboxylic acid component having a purity of 100% and 30 parts bymass of a tetracarboxylic acid component having a purity of 90% areused). When the purity is less than 98%, the molecular weight of thepolyimide precursor may not be sufficiently increased and the obtainedpolyimide may have low heat resistance. The purity is a value which maybe determined by gas chromatography analysis, liquid chromatographyanalysis or ¹H-NMR analysis, or the like. In the case of atetracarboxylic dianhydride, the purity may be determined by subjectingthe tetracarboxylic dianhydride to hydrolysis treatment to form atetracarboxylic acid, and determining the purity of the tetracarboxylicacid.

The purity of the diamine component to be used in the present inventionmay be preferably, but not limited to, 99% or more, more preferably99.5% or more. (In the case where a plurality of types of diaminecomponents are used, the purity is the value of the diamine componenthaving the highest purity, or the average value of the purities of alldiamine components to be used which are determined separately andweighted with the mass ratio of the used components; for example, thepurity of the diamine component used is calculated to be 97% when 70parts by mass of a diamine component having a purity of 100% and 30parts by mass of a diamine component having a purity of 90% are used).When the purity is less than 98%, the molecular weight of the polyimideprecursor may not be sufficiently increased and the obtained polyimidemay have low heat resistance. The purity is a value which may bedetermined by gas chromatography analysis, liquid chromatographyanalysis or ¹H-NMR analysis, or the like.

Norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like may be synthesized by the method described in PatentLiterature 6, and the like, although the method for synthesizingnorbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like is not limited thereto. As described in Non PatentLiterature 1,norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like may comprise several types of stereoisomers, whichdepends on the synthesis method.

Norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like, or an intermediate thereof may be subjected topurification by the use of column, or the like to isolate each one ofstereoisomers, or a mixture of several types of stereoisomers.

Single products of, or a mixture oftrans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like, andcis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like may be also obtained by subjectingnorbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicacid, or the like, or an intermediate thereof to purification by the useof column, or the like.

As for the polyimide precursor of the present invention [polyimideprecursors (A-1) (A-2) and (A-3)], when the tetracarboxylic acidcomponent and the diamine component comprise isomers, each one of theisomers may be isolated and used for the polymerization, or the like, oralternatively, the isomers as the mixture may be used for thepolymerization, or the like.

In the polyimide precursor of the present invention, X₁ and Y₁ in thechemical formula (1), X₂ and Y₂ in the chemical formula (3), X₃ and Y₃in the chemical formula (5), and X₄ and Y₄ in the chemical formula (6)are each independently hydrogen, an alkyl group having 1 to 6 carbonatoms, preferably having 1 to 3 carbon atoms, or an alkylsilyl grouphaving 3 to 9 carbon atoms. As for X₁, Y₁, X₂, Y₂, X₃, Y₃, X₄ and Y₄,the types of the functional groups and the introduction ratio of thefunctional groups may be changed by the production method as describedlater.

In the case where X₁, Y₁, X₂, Y₂, X₃, Y₃, X₄ and Y₄ are hydrogen, apolyimide tends to be easily produced therefrom.

Meanwhile, in the case where X₁, Y₁, X₂, Y₂, X₃, Y₃, X₄ and Y₄ are eachan alkyl group having 1 to 6 carbon atoms, preferably having 1 to 3carbon atoms, the polyimide precursor tends to have excellent storagestability. In this case, X₁, Y₁, X₂, Y₂, X₃, Y₃, X₄ and Y₄ are morepreferably methyl or ethyl.

Additionally, in the case where X₁, Y₁, X₂, Y₂, X₃, Y₃, X₄ and Y₄ areeach an alkylsilyl group having 3 to 9 carbon atoms, the polyimideprecursor tends to have excellent solubility. In this case, X₁, Y₁, X₂,Y₂, X₃, Y₃, X₄ and Y₄ are more preferably trimethylsilyl ort-butyldimethylsilyl.

When an alkyl group or an alkylsilyl group is introduced, X₁, Y₁, X₂,Y₂, X₃, Y₃, X₄ and Y₄ each may be converted into an alkyl group or analkylsilyl group in a ratio of 25% or more, preferably 50% or more, morepreferably 75% or more, although the introduction ratio of thefunctional groups is not limited thereto. When X₁, Y₁, X₂, Y₂, X₃, Y₃,X₄ and Y₄ each are converted into an alkyl group or an alkylsilyl groupin a ratio of 25% or more, the polyimide precursor may have excellentstorage stability.

According to the chemical structures X₁ and Y₁, X₂ and Y₂, X₃ and Y₃, orX₄ and Y₄ have, the polyimide precursors of the present invention may beeach independently classified into

1) polyamic acid (X₁ and Y₁, X₂ and Y₂, X₃ and Y₃, or X₄ and Y₄ arehydrogen),

2) polyamic acid ester (at least part of X₁ and Y₁ is an alkyl group, atleast part of X₂ and Y₂ is an alkyl group, at least part of X₃ and Y₃ isan alkyl group, or at least part of X₄ and Y₄ is an alkyl group), and

3) 4) polyamic acid silyl ester (at least part of X₁ and Y₁ is analkylsilyl group, at least part of X₂ and Y₂ is an alkylsilyl group, atleast part of X₃ and Y₃ is an alkylsilyl group, or at least part of X₄and Y₄ is an alkylsilyl group).

Each class of the polyimide precursors of the present invention may beeasily produced by the following production methods. However, the methodfor producing the polyimide precursor of the present invention is notlimited to the following production methods.

1) Polyamic Acid

The polyimide precursor of the present invention may be suitablyobtained, in the form of a polyimide precursor solution composition, byreacting a tetracarboxylic dianhydride as a tetracarboxylic acidcomponent and a diamine component in a substantially equimolar amount,preferably in a molar ratio of the diamine component to thetetracarboxylic acid component [molar number of the diaminecomponent/molar number of the tetracarboxylic acid component] of 0.90 to1.10, more preferably 0.95 to 1.05, in a solvent at a relatively lowtemperature of 120° C. or less, for example, to suppress theimidization.

More specifically, the polyimide precursor may be obtained by dissolvingthe diamine in an organic solvent, adding the tetracarboxylicdianhydride to the resulting solution gradually while stirring thesolution, and then stirring the solution at a temperature of 0° C. to120° C., preferably 5° C. to 80° C., for 1 hour to 72 hours, althoughthe method for synthesizing the polyimide precursor of the presentinvention is not limited thereto. When they are reacted at a temperatureof 80° C. or more, the molecular weight may vary depending on thetemperature history in the polymerization and the imidization mayproceed by heat, and therefore the polyimide precursor may not be stablyproduced. The sequence of the addition of the diamine and thetetracarboxylic dianhydride in the production method as described aboveis preferred because the molecular weight of the polyimide precursor isapt to increase. Meanwhile, the sequence of the addition of the diamineand the tetracarboxylic dianhydride in the production method asdescribed above may be reversed, and the sequence is preferred becausethe amount of the precipitate is reduced.

In addition, when the diamine component is excessive in the molar ratioof the tetracarboxylic acid component to the diamine component, acarboxylic acid derivative may be added in an amount which substantiallycorresponds to the excessive molar number of the diamine component, asnecessary, so that the molar ratio of the tetracarboxylic acid componentto the diamine component is closer to the substantially equimolaramount. As the carboxylic acid derivative to be used herein,tetracarboxylic acids, which do not substantially increase the viscosityof the polyimide precursor solution, that is, do not substantiallyinvolve the molecular chain extension, or tricarboxylic acids andanhydrides thereof, and dicarboxylic acids and anhydrides thereof, whichfunction as an end-stopping agent, and the like are preferred.

2) Polyamic Acid Ester

A diester dicarboxylic acid chloride may be obtained by reacting atetracarboxylic dianhydride and an arbitrary alcohol to provide adiester dicarboxylic acid, and then reacting the diester dicarboxylicacid and a chlorinating agent (thionyl chloride, oxalyl chloride, andthe like). The polyimide precursor may be obtained by stirring thediester dicarboxylic acid chloride and a diamine at a temperature of−20° C. to 120° C., preferably −5° C. to 80° C., for 1 hour to 72 hours.When they are reacted at a temperature of 80° C. or more, the molecularweight may vary depending on the temperature history in thepolymerization and the imidization may proceed by heat, and thereforethe polyimide precursor may not be stably produced. In addition, thepolyimide precursor may also be easily obtained bydehydrating/condensing a diester dicarboxylic acid and a diamine by theuse of a phosphorus-based condensing agent, a carbodiimide condensingagent, or the like.

The polyimide precursor obtained by the method is stable, and thereforethe polyimide precursor may be subjected to purification, for example,reprecipitation in which a solvent such as water and alcohols is addedthereto.

3) Polyamic Acid Silyl Ester (Indirect Method)

A silylated diamine may be obtained by reacting a diamine and asilylating agent in advance. The silylated diamine may be purified bydistillation, or the like, as necessary. And then, the polyimideprecursor may be obtained by dissolving the silylated diamine in adehydrated solvent, adding a tetracarboxylic dianhydride to theresulting solution gradually while stirring the solution, and thenstirring the solution at a temperature of 0° C. to 120° C., preferably5° C. to 80° C., for 1 hour to 72 hours. When they are reacted at atemperature of 80° C. or more, the molecular weight may vary dependingon the temperature history in the polymerization and the imidization mayproceed by heat, and therefore the polyimide precursor may not be stablyproduced.

As for the silylating agent to be used herein, the use of a silylatingagent containing no chlorine is preferred because it is unnecessary topurify the silylated diamine. Examples of the silylating agentcontaining no chlorine atom includeN,O-bis(trimethylsilyl)trifluoroacetamide,N,O-bis(trimethylsilyl)acetamide, and hexamethyldisilazane. Among them,N,O-bis(trimethylsilyl)acetamide, and hexamethyldisilazane areparticularly preferred, because they contain no fluorine atom and areinexpensive.

In addition, in the silylation reaction of diamine, an amine catalystsuch as pyridine, piperidine and triethylamine may be used so as toaccelerate the reaction. The catalyst may be used, as it is, as acatalyst for the polymerization of the polyimide precursor.

4) Polyamic Acid Silyl Ester (Direct Method)

The polyimide precursor may be obtained by mixing a polyamic acidsolution obtained by the method 1) and a silylating agent, and thenstirring the resulting mixture at a temperature of 0° C. to 120° C.,preferably 5° C. to 80° C., for 1 hour to 72 hours. When they arereacted at a temperature of 80° C. or more, the molecular weight mayvary depending on the temperature history in the polymerization and theimidization may proceed by heat, and therefore the polyimide precursormay not be stably produced.

As for the silylating agent to be used herein, the use of a silylatingagent containing no chlorine is preferred because it is unnecessary topurify the silylated polyamic acid, or the obtained polyimide. Examplesof the silylating agent containing no chlorine atom includeN,O-bis(trimethylsilyl)trifluoroacetamide,N,O-bis(trimethylsilyl)acetamide, and hexamethyldisilazane. Among them,N,O-bis(trimethylsilyl)acetamide, and hexamethyldisilazane areparticularly preferred, because they contain no fluorine atom and areinexpensive.

All of the production methods as described above may be suitablyperformed in an organic solvent, and as a consequence a varnish of thepolyimide precursor of the present invention may be easily obtained.

As the solvent used in the production of the polyimide precursor, forexample, aprotic solvents such as N,N-dimethylformamide,N,N-dimethylacetamide, N-methyl-2-pyrrolidone,1,3-dimethyl-2-imidazolidinone and dimethyl sulfoxide are preferred, andN,N-dimethylacetamide and N-methyl-2-pyrrolidone are particularlypreferred. However, any solvent may be used without any trouble on thecondition that the starting monomer components and the formed polyimideprecursor can be dissolved in the solvent, and the structure of thesolvent is not limited thereto. Examples of the solvent preferablyemployed include amide solvents such as N,N-dimethylformamide,N,N-dimethylacetamide and N-methylpyrrolidone; cyclic ester solventssuch as γ-butyrolactone, γ-valerolactone, δ-valerolactone,γ-caprolactone, ε-caprolactone and α-methyl-γ-butyrolactone; carbonatesolvents such as ethylene carbonate and propylene carbonate; glycolsolvents such as triethylene glycol; phenol solvents such as m-cresol,p-cresol, 3-chlorophenol and 4-chlorophenol; acetophenone,1,3-dimethyl-2-imidazolidinone, sulfolane, and dimethylsulfoxide. Inaddition, other common organic solvents, namely, phenol, o-cresol, butylacetate, ethyl acetate, isobutyl acetate, propyleneglycol methylacetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolveacetate, ethyl cellosolve acetate, butyl cellosolve acetate,tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether,diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutylketone, cyclopentanone, cyclohexanone, methyl ethyl ketone, acetone,butanol, ethanol, xylene, toluene, chlorobenzene, turpentine, mineralspirits, petroleum naphtha-based solvents, and the like may be used.These solvents may be used in combination of a plurality of types.

In the present invention, although the logarithmic viscosity of thepolyimide precursor is not limited thereto, the logarithmic viscosity ofthe polyimide precursor in a N,N-dimethylacetamide solution at aconcentration of 0.5 g/dL at 30° C. may be preferably 0.2 dL/g or more,more preferably 0.8 dL/g or more, particularly preferably 0.9 dL/g ormore. When the logarithmic viscosity is 0.2 dL/g or more, the molecularweight of the polyimide precursor is high, and therefore the obtainedpolyimide may have excellent mechanical strength and heat resistance.

In the present invention, it is preferred that the varnish of thepolyimide precursor comprises at least the polyimide precursor of thepresent invention and a solvent, and the total amount of thetetracarboxylic acid component and the diamine component is 5 mass % ormore, preferably 10 mass % or more, more preferably 15 mass % or more,based on the total amount of the solvent, the tetracarboxylic acidcomponent and the diamine component. Additionally, it is generallypreferred that the total amount is 60 mass % or less, preferably 50 mass% or less. When the concentration, which is approximate to theconcentration of the solid content based on the polyimide precursor, istoo low, it may be difficult to control the thickness of the obtainedpolyimide film in the production of the polyimide film, for example.

As the solvent used for the varnish of the polyimide precursor of thepresent invention, any solvent may be used without any trouble on thecondition that the polyimide precursor can be dissolved in the solvent,and the structure of the solvent is not particularly limited. Examplesof the solvent preferably employed include amide solvents such asN,N-dimethylformamide, N,N-dimethylacetamide and N-methyl-2-pyrrolidone;cyclic ester solvents such as γ-butyrolactone, γ-valerolactone,δ-valerolactone, γ-caprolactone, ε-caprolactone andα-methyl-γ-butyrolactone; carbonate solvents such as ethylene carbonateand propylene carbonate; glycol solvents such as triethylene glycol;phenol solvents such as m-cresol, p-cresol, 3-chlorophenol and4-chlorophenol; acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane,and dimethylsulfoxide. In addition, other common organic solvents,namely, phenol, o-cresol, butyl acetate, ethyl acetate, isobutylacetate, propyleneglycol methyl acetate, ethyl cellosolve, butylcellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butylcellosolve acetate, tetrahydrofuran, dimethoxyethane, diethoxyethane,dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone,diisobutyl ketone, cyclopentanone, cyclohexanone, methyl ethyl ketone,acetone, butanol, ethanol, xylene, toluene, chlorobenzene, turpentine,mineral spirits, petroleum naphtha-based solvents, and the like may beused. Additionally, these may be used in combination of a plurality oftypes.

In the present invention, although the viscosity (rotational viscosity)of the varnish of the polyimide precursor is not limited thereto, therotational viscosity, which is measured with an E-type rotationalviscometer at a temperature of 25° C. and at a shearing speed of 20sec⁻¹, may be preferably 0.01 to 1000 Pa-sec, more preferably 0.1 to 100Pa-sec. In addition, thixotropy may be imparted, as necessary. When theviscosity is within the above-mentioned range, the varnish is easy tohandle during the coating or the film formation, and the varnish is lessrepelled and has excellent leveling property, and therefore a good filmmay be obtained.

As necessary, a chemical imidizing agent (an acid anhydride such asacetic anhydride, and an amine compound such as pyridine andisoquinoline), an anti-oxidizing agent, a filler, a dye, a pigment, acoupling agent such as a silane coupling agent, a primer, a flameretardant, a defoaming agent, a leveling agent, a rheology control agent(flow-promoting agent), a releasing agent, and the like may be added tothe varnish of the polyimide precursor of the present invention.

As necessary, an inorganic particle such as silica may be mixed into thevarnish of the polyimide precursor of the present invention. Examples ofthe mixing method include, but not limited to, a method in which aninorganic particle is dispersed in a polymerization solvent, and then apolyimide precursor is polymerized in the solvent; a method in which apolyimide precursor solution and an inorganic particle are mixed; amethod in which a polyimide precursor solution and an inorganic particledispersion are mixed; and a method in which an inorganic particle isadded to and mixed with a polyimide precursor solution. For example, asilica particle or a silica particle dispersion may be added to thevarnish of the polyimide precursor of the present invention. As for thesilica particle to be added, the particle size is preferably 100 nm orless, more preferably 50 nm or less, particularly preferably 30 nm orless. When the particle size of the silica particle to be added is morethan 100 nm, the polyimide may be white-turbid. Additionally, in thecase where a silica particle dispersion is added to the varnish,“ORGANOSILICASOL DMAc-ST (primary particle size: 10-15 nm, dispersionsolvent: N,N-dimethylacetamide) solid content: 20-21%” made by NissanChemical Industries, Ltd., and the like may be used, for example.

The polyimide (B-1) of the first invention comprises at least onerepeating unit represented by the chemical formula (8), and the totalcontent of the repeating units represented by the chemical formula (8)is 50 mol % or more based on the total repeating units. In other words,the polyimide (B-1) of the first invention may be obtained using thetetracarboxylic acid component and the diamine component used to obtainthe polyimide precursor (A-1) of the first invention as described above.The polyimide (B-1) of the first invention may be suitably produced bythe dehydration/ring closure reaction (imidization reaction) of thepolyimide precursor (A-1) of the first invention as described above. Theimidization method is not particularly limited, and any known thermalimidization or chemical imidization method may be suitably applied.

The polyimide (B-1) of the first invention preferably comprises at leastone repeating unit of the chemical formula (8) in which B₁ is a grouprepresented by the chemical formula (9). The chemical formula (8)corresponds to the chemical formula (1) of the polyimide precursor (A-1)of the first invention, and the chemical formula (9) corresponds to thechemical formula (2) of the polyimide precursor (A-1) of the firstinvention. The steric structure is usually maintained after theimidization, and therefore the polyimide (B-1) of the first invention,which is obtained by imidizing the polyimide precursor (A-1) of thefirst invention, has the same steric structure as the polyimideprecursor (A-1) has, and the repeating unit of the chemical formula (8)has the same steric structure as the repeating unit of the chemicalformula (1) has.

The polyimide (B-2) of the second invention comprises at least onerepeating unit represented by the chemical formula (10), and the totalcontent of the repeating units represented by the chemical formula (10)is 30 mol % or more based on the total repeating units. In other words,the polyimide (B-2) of the second invention may be obtained using thetetracarboxylic acid component and the diamine component used to obtainthe polyimide precursor (A-2) of the second invention as describedabove. The polyimide (B-2) of the second invention may be suitablyproduced by the dehydration/ring closure reaction (imidization reaction)of the polyimide precursor (A-2) of the second invention as describedabove. The imidization method is not particularly limited, and any knownthermal imidization or chemical imidization method may be suitablyapplied.

The polyimide (B-2) of the second invention preferably comprises atleast one repeating unit of the chemical formula (10) in which B₂ is agroup represented by the chemical formula (11). The chemical formula(10) corresponds to the chemical formula (3) of the polyimide precursor(A-2) of the second invention, and the chemical formula (11) correspondsto the chemical formula (4) of the polyimide precursor (A-2) of thesecond invention. The steric structure is usually maintained after theimidization, and therefore the polyimide (B-2) of the second invention,which is obtained by imidizing the polyimide precursor (A-2) of thesecond invention, has the same steric structure as the polyimideprecursor (A-2) has, and the repeating unit of the chemical formula (10)has the same steric structure as the repeating unit of the chemicalformula (3) has.

The polyimide (B-3) of the third invention comprises at least one ofrepeating units represented by the chemical formula (12) and thechemical formula (13), and the total content of the repeating unitsrepresented by the chemical formula (12) and the chemical formula (13)is 80 mol % or more based on the total repeating units. In other words,the polyimide (B-3) of the third invention may be obtained using thetetracarboxylic acid component and the diamine component used to obtainthe polyimide precursor (A-3) of the third invention as described above.The polyimide (B-3) of the third invention may be suitably produced bythe dehydration/ring closure reaction (imidization reaction) of thepolyimide precursor (A-3) of the third invention as described above. Theimidization method is not particularly limited, and any known thermalimidization or chemical imidization method may be suitably applied.

The polyimide (B-3) of the third invention preferably comprises at leastone of repeating units of the chemical formula (12) and the chemicalformula (13) in which B₃ is a group represented by the chemical formula(14). The chemical formula (12) corresponds to the chemical formula (5)of the polyimide precursor (A-3) of the third invention and the chemicalformula (13) corresponds to the chemical formula (6) of the polyimideprecursor (A-3) of the third invention, and the chemical formula (14)corresponds to the chemical formula (7) of the polyimide precursor (A-3)of the third invention. The steric structure is usually maintained afterthe imidization, and therefore the polyimide (B-3) of the thirdinvention, which is obtained by imidizing the polyimide precursor (A-3)of the third invention, has the same steric structure as the polyimideprecursor (A-3) has, and the repeating unit of the chemical formula (12)has the same steric structure as the repeating unit of the chemicalformula (5) has and the repeating unit of the chemical formula (13) hasthe same steric structure as the repeating unit of the chemical formula(6) has.

Preferred examples of the form of the obtained polyimide include a film,a laminate of a polyimide film and another substrate, a coating film, apowder, a bead, a molded article, a foamed article, and a varnish.

In the present invention, although the logarithmic viscosity of thepolyimide is not limited thereto, the logarithmic viscosity of thepolyimide in a N,N-dimethylacetamide solution at a concentration of 0.5g/dL at 30° C. may be preferably 0.2 dL/g or more, more preferably 0.4dL/g or more, particularly preferably 0.5 dL/g or more. When thelogarithmic viscosity is 0.2 dL/g or more, the obtained polyimide mayhave excellent mechanical strength and heat resistance.

In the present invention, it is preferred that the varnish of thepolyimide comprises at least the polyimide of the present invention anda solvent, and the amount of the polyimide is 5 mass % or more,preferably 10 mass % or more, more preferably 15 mass % or more,particularly preferably 20 mass % or more, based on the total amount ofthe solvent and the polyimide. When the concentration is too low, it maybe difficult to control the thickness of the obtained polyimide film inthe production of the polyimide film, for example.

As the solvent used for the varnish of the polyimide of the presentinvention, any solvent may be used without any trouble on the conditionthat the polyimide can be dissolved in the solvent, and the structure ofthe solvent is not particularly limited. The solvent used for thevarnish of the polyimide precursor of the present invention as describedabove may be used likewise as the solvent.

In the present invention, although the viscosity (rotational viscosity)of the varnish of the polyimide is not limited thereto, the rotationalviscosity, which is measured with an E-type rotational viscometer at atemperature of 25° C. and at a shearing speed of 20 sec⁻¹, may bepreferably 0.01 to 1000 Pa-sec, more preferably 0.1 to 100 Pa-sec. Inaddition, thixotropy may be imparted, as necessary. When the viscosityis within the above-mentioned range, the varnish is easy to handleduring the coating or the film formation, and the varnish is lessrepelled and has excellent leveling property, and therefore a good filmmay be obtained.

As necessary, an anti-oxidizing agent, a filler, a dye, a pigment, acoupling agent such as a silane coupling agent, a primer, a flameretardant, a defoaming agent, a leveling agent, a rheology control agent(flow-promoting agent), a releasing agent, and the like may be added tothe varnish of the polyimide of the present invention.

As necessary, an inorganic particle such as silica may be mixed into thepolyimide obtained from the polyimide precursor of the present inventionand the polyimide of the present invention. Examples of the mixingmethod include, but not limited to, a method in which an inorganicparticle is dispersed in a polymerization solvent, and then a polyimideprecursor is polymerized in the solvent; a method in which a polyimideprecursor solution and an inorganic particle are mixed; a method inwhich a polyimide precursor solution and an inorganic particledispersion are mixed; a method in which an inorganic particle is mixedinto a polyimide solution; and a method in which an inorganic particledispersion is mixed into a polyimide solution. A silica-containingpolyimide may be obtained by imidizing a polyimide precursor in asilica-dispersed polyimide precursor solution in which silica isdispersed by any one of these methods; or by mixing a polyimide solutionwith a silica particle or a silica-dispersed solution, and then heatingand drying the mixture to remove the solvent therefrom. As for theinorganic particle to be dispersed in the polyimide, a silica particlemay be added to the polyimide. As for the silica particle to be added,the particle size is preferably 100 nm or less, more preferably 50 nm orless, particularly preferably 30 nm or less. When the particle size ofthe silica particle to be added is more than 100 nm, the polyimide maybe white-turbid. Additionally, in the case where a silica particledispersion is used, “ORGANOSILICASOL DMAc-ST (primary particle size:10-15 nm, dispersion solvent: N,N-dimethylacetamide) solid content:20-21%” made by Nissan Chemical Industries, Ltd., and the like may beused, for example.

The polyimide obtained from the polyimide precursor of the presentinvention and the polyimide of the present invention may havepreferably, but not limited to, a coefficient of linear thermalexpansion from 50° C. to 400° C. of 45 ppm/K or less, more preferably 30ppm/K or less, more preferably 25 ppm/K or less, more preferably 24ppm/K or less, more preferably 22 ppm/K or less, particularly preferably20 ppm/K or less, when the polyimide is formed into a film, and have avery low coefficient of linear thermal expansion up to a hightemperature. When the coefficient of linear thermal expansion is great,the difference in coefficient of linear thermal expansion between thepolyimide and a conductive material such as a metal is great, andtherefore a trouble such as an increase in warpage may occur during theformation of a circuit board.

The polyimide obtained from the polyimide precursor of the presentinvention and the polyimide of the present invention may havepreferably, but not limited to, a light transmittance at 400 nm of 70%or more, more preferably 75% or more, more preferably 77% or more, morepreferably 78% or more, more preferably 79% or more, particularlypreferably 80% or more, in the form of a film having a thickness of 10μm, and have excellent optical transparency. When the lighttransmittance is low, the light source must be bright, and therefore aproblem of more energy required, or the like may arise in the case wherethe polyimide is used in display application, or the like.

The polyimide obtained from the polyimide precursor of the presentinvention and the polyimide of the present invention may havepreferably, but not limited to, a total light transmittance (averagelight transmittance at wavelengths of 380 nm to 780 nm) of 85% or more,more preferably 86% or more, more preferably 87% or more, particularlypreferably 88% or more, in the form of a film having a thickness of 10μm, and have excellent optical transparency. When the total lighttransmittance is low, the light source must be bright, and therefore aproblem of more energy required, or the like may arise in the case wherethe polyimide is used in display application, or the like.

As for a film formed of the polyimide of the present invention, thethickness of the film is preferably 1 μm to 250 μm, more preferably 1 μmto 150 μm, more preferably 1 μm to 50 μm, particularly preferably 1 μmto 30 μm, although it varies depending on the intended use. When thepolyimide film is too thick, the light transmittance may be low in thecase where the polyimide film is used in applications where light passesthrough the polyimide film.

The polyimide obtained from the polyimide precursor of the presentinvention and the polyimide of the present invention may havepreferably, but not limited to, a 5% weight loss temperature of morethan 470° C., more preferably 480° C. or more, more preferably 490° C.or more, particularly preferably 495° C. or more. In the case where agas barrier film, or the like is formed on the polyimide for theformation of a transistor on the polyimide, or the like, swelling mayoccur between the polyimide and the barrier film due to outgassingassociated with the decomposition of the polyimide, or the like when theheat resistance is low.

The polyimide obtained from the polyimide precursor of the presentinvention and the polyimide of the present invention has excellentproperties such as high transparency, bending resistance and high heatresistance, and has a very low coefficient of linear thermal expansionup to a high temperature, and therefore the polyimide may be suitablyused in the applications of transparent substrate for display,transparent substrate for touch panel, or substrate for solar battery.

One example of a method for producing a polyimide film/base laminate, ora polyimide film with the use of the polyimide precursor of the presentinvention will be described hereinafter. However, the method is notlimited to the following method.

For example, a varnish of the polyimide precursor of the presentinvention is flow-cast on a base of ceramic (glass, silicon, oralumina), metal (copper, aluminum, or stainless steel), heat-resistantplastic film (polyimide), or the like, and dried at a temperature of 20°C. to 180° C., preferably 20° C. to 150° C., by the use of hot air orinfrared ray in a vacuum, in an inert gas such as nitrogen, or in air.And then, the obtained polyimide precursor film is heated and imidizedat a temperature of 200° C. to 500° C., more preferably about 250° C. toabout 450° C., by the use of hot air or infrared ray in a vacuum, in aninert gas such as nitrogen, or in air, wherein the polyimide precursorfilm is on the base, or alternatively, the polyimide precursor film ispeeled from the base and fixed at the edges, to provide a polyimidefilm/base laminate, or a polyimide film. The thermal imidization ispreferably performed in a vacuum or in an inert gas so as to preventoxidation and degradation of the obtained polyimide film. The thermalimidization may be performed in air if the thermal imidizationtemperature is not too high. At this point, the thickness of thepolyimide film (the polyimide film layer, in the case of a polyimidefilm/base laminate) is preferably 1 μm to 250 μm, more preferably 1 μmto 150 μm, in view of the transportability in the subsequent steps.

The imidization reaction of the polyimide precursor may also beperformed by chemical treatment in which the polyimide precursor isimmersed in a solution containing a dehydrating/cyclizing agent such asacetic anhydride in the presence of a tertiary amine such as pyridineand triethylamine, instead of the thermal imidization by heat treatmentas described above. Alternatively, a partially-imidized polyimideprecursor may be prepared by adding the dehydrating/cyclizing agent tothe varnish of the polyimide precursor in advance and stirring thevarnish, and then flow-casting the varnish on a base and drying it. Apolyimide film/base laminate, or a polyimide film may be obtained byfurther heating the partially-imidized polyimide precursor as describedabove.

A flexible conductive substrate may be obtained by forming a conductivelayer on one surface or both surfaces of the polyimide film/baselaminate or the polyimide film thus obtained.

A flexible conductive substrate may be obtained by the followingmethods, for example. As for the first method, the polyimide film is notpeeled from the base in the “polyimide film/base” laminate, and aconductive layer of a conductive material (metal or metal oxide,conductive organic material, conductive carbon, or the like) is formedon the surface of the polyimide film by sputtering, vapor deposition,printing, or the like, to provide a conductive laminate of “conductivelayer/polyimide film/base”. And then, as necessary, the “conductivelayer/polyimide film” laminate is peeled from the base, to provide atransparent and flexible conductive substrate which consists of the“conductive layer/polyimide film” laminate.

As for the second method, the polyimide film is peeled from the base inthe “polyimide film/base” laminate to obtain the polyimide film, andthen a conductive layer of a conductive material (metal or metal oxide,conductive organic material, conductive carbon, or the like) is formedon the surface of the polyimide film in the same way as in the firstmethod, to provide a transparent and flexible conductive substrate whichconsists of the “conductive layer/polyimide film” laminate or“conductive layer/polyimide film/conductive layer” laminate.

In the first and the second methods, a gas barrier layer against watervapor, oxygen, or the like, and an inorganic layer such as alight-controlling layer may be formed on the surface of the polyimidefilm by sputtering, vapor deposition, gel-sol process, or the like, asnecessary, before the conductive layer is formed.

In addition, a circuit may be suitably formed on the conductive layer byphotolithography process, various printing processes, ink-jet process,or the like.

The substrate of the present invention comprises a circuit of aconductive layer on a surface of a polyimide film formed of thepolyimide of the present invention, optionally with a gas barrier layeror an inorganic layer therebetween, as necessary. The substrate isflexible, and excellent in high transparency, bending resistance andheat resistance, and also has a very low coefficient of linear thermalexpansion up to a high temperature and excellent solvent resistance, andtherefore a fine circuit may be easily formed thereon. Accordingly, thesubstrate may be suitably used as a substrate for display, touch panel,or solar battery.

More specifically, a flexible thin-film transistor is produced byfurther forming a transistor (inorganic transistor, or organictransistor) on the substrate by vapor deposition, various printingprocesses, ink-jet process, or the like, and is suitably used as aliquid crystal device for display device, an EL device, or aphotoelectric device.

EXAMPLES

The present invention will be further described hereinafter withreference to Examples and Comparative Examples. However, the presentinvention is not limited to the following Examples.

In each of the following Examples, the evaluations were conducted by thefollowing methods.

<Evaluation of Varnish of Polyimide Precursor>

[Logarithmic Viscosity]

A polyimide precursor solution at a concentration of 0.5 g/dL wasprepared by diluting the varnish with the solvent used in thepolymerization, and the logarithmic viscosity was determined by themeasurement of the viscosity at 30° C. using an Ubbelohde viscometer.

<Evaluation of Polyimide Film>

[Light Transmittance at 400 nm, Total Light Transmittance]

The light transmittance at 400 nm and the total light transmittance(average light transmittance at 380 nm to 780 nm) of the polyimide filmhaving a thickness of about 10 μm were measured using a MCPD-300 made byOtsuka Electronics Co., Ltd. The light transmittance at 400 nm and thetotal light transmittance of the film having a thickness of 10 μm werecalculated from the measured light transmittance at 400 nm and themeasured total light transmittance using the Lambert-Beer formula on theassumption that the reflectance was 10%. The calculating formulas areshown below.

Log₁₀((T ₁+10)/100)=10/L×(Log₁₀((T ₁′+10)/100))

Log₁₀((T ₂+10)/100)=10/L×(Log₁₀((T ₂′+10)/100))

T₁: light transmittance at 400 nm of the polyimide film having athickness of10 μm on the assumption that the reflectance was 10% (%)T₁′: measured light transmittance at 400 nm (%)T₂: total light transmittance of the polyimide film having a thicknessof 10 μm on the assumption that the reflectance was 10% (%)T₂′: measured total light transmittance (%)L: thickness of the polyimide film measured (μm)

[Modulus of Elasticity, Elongation at Break]

The polyimide film having a thickness of about 10 μm was cut to thedumbbell shape of IEC450 standard, which was used as a test piece, andthe initial modulus of elasticity and the elongation at break weremeasured at a distance between chucks of 30 mm and a tensile speed of 2mm/min using a TENSILON made by Orientec Co., Ltd.

[Coefficient of Linear Thermal Expansion (CTE)]

The polyimide film having a thickness of about 10 μm was cut to arectangle having a width of 4 mm, which was used as a test piece, andthe test piece was heated to 500° C. at a distance between chucks of 15mm, a load of 2 g and a temperature-increasing rate of 20° C./min usinga TMA/SS6100 made by SII Nanotechnology Inc. The coefficient of linearthermal expansion from 50° C. to 400° C. was determined from theobtained TMA curve.

[5% Weight Loss Temperature]

The polyimide film having a thickness of about 10 μm was used as a testpiece, and the test piece was heated from 25° C. to 600° C. at atemperature-increasing rate of 10° C./min in a flow of nitrogen using athermogravimetric analyzer (Q5000IR) made by TA Instruments Inc. The 5%weight loss temperature was determined from the obtained weight curve.

The abbreviations, purities, etc. of the raw materials used in each ofthe following Examples are as follows.

[Diamine Component]

DABAN: 4,4′-diaminobenzanilide [purity: 99.90% (GC analysis)]TFMB: 2,2′-bis(trifluoromethyl)benzidine [purity: 99.83% (GC analysis)]PPD: p-phenylenediamine [purity: 99.9% (GC analysis)]m-TD: m-tolidine [purity: 99.84% (GC analysis)]BAPT: bis(4-aminophenyl)terephthalate [purity: 99.56% (LC analysis)]4-APTP: N,N′-bis(4-aminophenyl)terephthalamide [purity: 99.95% (GCanalysis)]FDA: 9,9-bis(4-aminophenyl)fluorene4,4′-ODA: 4,4′-oxydianiline [purity: 99.9% (GC analysis)]BAPB: 4,4′-bis(4-aminophenoxy)biphenylTPE-R: 1,3-bis(4-aminophenoxy)benzeneMPD: m-phenylenediamine3,4′-ODA: 3,4′-oxydianilineASD: bis(4-aminophenyl)sulfide

[Tetracarboxylic Acid Component]

CpODAt-en-en:trans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicdianhydrideCpODAc-en-en:cis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicdianhydrideCpODAt-ex-en:trans-exo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro2″-norbornane-5,5″,6,6″-tetracarboxylic dianhydrideCpODAt-ex-ex:trans-exo-exo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicdianhydrideCpODAc-ex-en:cis-exo-endo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicdianhydrideCpODAc-ex-ex:cis-exo-exo-norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylicdianhydride

CpODA-en: Mixture of CpODAt-en-en (63.0 wt %) and CpODAc-en-en (37.0 wt%)

CpODA-en1: Mixture of CpODAt-en-en, CpODAc-en-en, CpODAt-ex-en,CpODAt-ex-ex, CpODAc-ex-en and CpODAc-ex-ex, in which the total contentof CpODAt-en-en and CpODAc-en-en is 83 wt %, and the total content ofCpODAt-ex-en, CpODAt-ex-ex, CpODAc-ex-en and CpODAc-ex-ex is 17 wt %.CpODA-en2: Mixture of CpODAt-en-en, CpODAc-en-en, CpODAt-ex-en,CpODAt-ex-ex, CpODAc-ex-en and CpODAc-ex-ex, in which the total contentof CpODAt-en-en and CpODAc-en-en is 97 wt %, and the total content ofCpODAt-ex-en, CpODAt-ex-ex, CpODAc-ex-en and CpODAc-ex-ex is 3 wt %.CpODA-en3: Mixture of CpODAt-en-en, CpODAc-en-en, CpODAt-ex-en,CpODAt-ex-ex, CpODAc-ex-en and CpODAc-ex-ex, in which the total contentof CpODAt-en-en and CpODAc-en-en is 98 wt %, and the total content ofCpODAt-ex-en, CpODAt-ex-ex, CpODAc-ex-en and CpODAc-ex-ex is 2 wt %.CpODA-en4: Mixture of CpODAt-en-en, CpODAc-en-en, CpODAt-ex-en,CpODAt-ex-ex, CpODAc-ex-en and CpODAc-ex-ex, in which the total contentof CpODAt-en-en and CpODAc-en-en is 99 wt %, and the total content ofCpODAt-ex-en, CpODAt-ex-ex, CpODAc-ex-en and CpODAc-ex-ex is 1 wt %.

CpODA: Mixture of CpODAt-en-en (49.8 wt %), CpODAc-en-en (29.2 wt %),CpODAt-ex-en (10.1 wt %), CpODAt-ex-ex (0.4 wt %), CpODAc-ex-en (10.1 wt%) and CpODAc-ex-ex (0.4 wt %)

DNDAxx:(4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2t,3t,6c,7c-tetracarboxylicdianhydride [purity as DNDAxx: 99.2% (GC analysis)]

[Solvent]

DMAc: N,N-dimethylacetamide

NMP—: N-methyl-2-pyrrolidone

[Purity of Solvent]

GC analysis:

Retention time of the main component (min) 14.28

Area of the main component (%) 99.9929

Peak area of the impurity having a shorter retention time (%) 0.0000

Peak area of the impurity having a longer retention time (%) 0.0071

Involatile component (mass %)<0.001Light transmittance (optical path length 1 cm, 400 nm):

Light transmittance before heating-reflux (%) 92

Light transmittance after heating-reflux for 3 hours in a nitrogenatmosphere (%) 92

Metal content:

Na (ppb) 150

Fe (ppb)<2

Cu (ppb)<2

Mo (ppb)<1

The structural formulas of the tetracarboxylic acid components and thediamine components used in Examples and Comparative Examples are shownin Table 1.

TABLE 1 Tetracarboxylic dianhydride Diamine

Example 1

CpODA-en was provided as the tetracarboxylic acid component. 2.27 g (10mmol) of DABAN was placed in a reaction vessel, which was purged withnitrogen gas, and 21.66 g of N,N-dimethylacetamide was added theretosuch that the total mass of loading monomers (total mass of the diaminecomponent and the carboxylic acid component) was 22 mass %, and then themixture was stirred at room temperature for 1 hour. 3.84 g (10 mmol) ofCpODA-en was gradually added to the resulting solution. The mixture wasstirred at room temperature for 12 hours, to provide a homogeneous andviscous polyimide precursor solution. The logarithmic viscosity of theobtained polyimide precursor was 1.4 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-1.

Example 2

CpODA-en was provided as the tetracarboxylic acid component. 2.12 g (10mmol) of m-TD was placed in a reaction vessel, which was purged withnitrogen gas, and 27.15 g of N,N-dimethylacetamide was added theretosuch that the total mass of loading monomers (total mass of the diaminecomponent and the carboxylic acid component) was 18 mass %, and then themixture was stirred at room temperature for 1 hour. 3.84 g (10 mmol) ofCpODA-en was gradually added to the resulting solution. The mixture wasstirred at room temperature for 12 hours, to provide a homogeneous andviscous polyimide precursor solution. The logarithmic viscosity of theobtained polyimide precursor was 1.0 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-1.

Example 3

CpODA-en was provided as the tetracarboxylic acid component. 3.48 g (10mmol) of BAPT was placed in a reaction vessel, which was purged withnitrogen gas, and 44.97 g of N,N-dimethylacetamide was added theretosuch that the total mass of loading monomers (total mass of the diaminecomponent and the carboxylic acid component) was 14 mass %, and then themixture was stirred at room temperature for 1 hour. 3.84 g (10 mmol) ofCpODA-en was gradually added to the resulting solution. The mixture wasstirred at room temperature for 12 hours, to provide a homogeneous andviscous polyimide precursor solution. The logarithmic viscosity of theobtained polyimide precursor was 1.8 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-1.

Example 4

CpODA-en was provided as the tetracarboxylic acid component. 3.46 g (10mmol) of 4-APTP was placed in a reaction vessel, which was purged withnitrogen gas, and 48.85 g of N,N-dimethylacetamide was added theretosuch that the total mass of loading monomers (total mass of the diaminecomponent and the carboxylic acid component) was 13 mass %, and then themixture was stirred at room temperature for 1 hour. 3.84 g (10 mmol) ofCpODA-en was gradually added to the resulting solution. The mixture wasstirred at room temperature for 12 hours, to provide a homogeneous andviscous polyimide precursor solution. The logarithmic viscosity of theobtained polyimide precursor was 2.2 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-1.

Example 5

CpODA-en was provided as the tetracarboxylic acid component. 1.14 g (5mmol) of DABAN and 1.60 g (5 mmol) of TFMB were placed in a reactionvessel, which was purged with nitrogen gas, and 19.74 g ofN,N-dimethylacetamide was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 25 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en was gradually addedto the resulting solution. The mixture was stirred at room temperaturefor 12 hours, to provide a homogeneous and viscous polyimide precursorsolution. The logarithmic viscosity of the obtained polyimide precursorwas 0.8 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-1.

Example 6

CpODA-en was provided as the tetracarboxylic acid component. 1.59 g (7mmol) of DABAN and 0.96 g (3 mmol) of TFMB were placed in a reactionvessel, which was purged with nitrogen gas, and 19.17 g ofN,N-dimethylacetamide was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 25 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en was gradually addedto the resulting solution. The mixture was stirred at room temperaturefor 12 hours, to provide a homogeneous and viscous polyimide precursorsolution. The logarithmic viscosity of the obtained polyimide precursorwas 0.9 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-1.

Example 7

CpODA-en was provided as the tetracarboxylic acid component. 1.59 g (7mmol) of DABAN and 0.32 g (3 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 19.25 g ofN,N-dimethylacetamide was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 23 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en was gradually addedto the resulting solution. The mixture was stirred at room temperaturefor 12 hours, to provide a homogeneous and viscous polyimide precursorsolution. The logarithmic viscosity of the obtained polyimide precursorwas 1.0 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-1.

Example 8

CpODA-en was provided as the tetracarboxylic acid component. 1.14 g (5mmol) of DABAN and 0.54 g (5 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 26.95 g ofN,N-dimethylacetamide was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 17 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en was gradually addedto the resulting solution. The mixture was stirred at room temperaturefor 12 hours, to provide a homogeneous and viscous polyimide precursorsolution. The logarithmic viscosity of the obtained polyimide precursorwas 0.9 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-1.

Example 9

CpODA-en was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN and 0.65 g (6 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 23.02 g ofN-methyl-2-pyrrolidone was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 19 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en was gradually addedto the resulting solution. The mixture was stirred at room temperaturefor 12 hours, to provide a homogeneous and viscous polyimide precursorsolution. The logarithmic viscosity of the obtained polyimide precursorwas 0.2 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 m.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-1.

Example 10

CpODA-en was provided as the tetracarboxylic acid component. 0.68 g (3mmol) of DABAN and 0.76 g (7 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 32.43 g ofN,N-dimethylacetamide was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 14 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en was gradually addedto the resulting solution. The mixture was stirred at room temperaturefor 12 hours, to provide a homogeneous and viscous polyimide precursorsolution. The logarithmic viscosity of the obtained polyimide precursorwas 0.9 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-1.

Example 11

CpODA-en was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN, 0.43 g (4 mmol) of PPD and 0.64 g (2 mmol) of TFMB wereplaced in a reaction vessel, which was purged with nitrogen gas, and28.42 g of N,N-dimethylacetamide was added thereto such that the totalmass of loading monomers (total mass of the diamine component and thecarboxylic acid component) was 17 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en wasgradually added to the resulting solution. The mixture was stirred atroom temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution. The logarithmic viscosity of the obtainedpolyimide precursor was 0.8 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-1.

Example 12

CpODA-en was provided as the tetracarboxylic acid component. 1.14 g (5mmol) of DABAN, 0.43 g (4 mmol) of PPD and 0.20 g (1 mmol) of 4,4′-ODAwere placed in a reaction vessel, which was purged with nitrogen gas,and 21.10 g of N,N-dimethylacetamide was added thereto such that thetotal mass of loading monomers (total mass of the diamine component andthe carboxylic acid component) was 21 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en wasgradually added to the resulting solution. The mixture was stirred atroom temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution. The logarithmic viscosity of the obtainedpolyimide precursor was 1.1 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor solution was heated on the glass substrate from roomtemperature to 420° C. in a nitrogen atmosphere (oxygen concentration:200 ppm or less), to provide a colorless and transparent polyimidefilm/glass laminate. Subsequently, the obtained polyimide film/glasslaminate was immersed in water, and then the polyimide film was peeledfrom the glass and dried, to provide a polyimide film having a thicknessof about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-1.

Example 13

CpODA-en1 was provided as the tetracarboxylic acid component. 3.46 g (10mmol) of 4-APTP was placed in a reaction vessel, which was purged withnitrogen gas, and 48.85 g of N-methyl-2-pyrrolidone was added theretosuch that the total mass of loading monomers (total mass of the diaminecomponent and the carboxylic acid component) was 13 mass %, and then themixture was stirred at room temperature for 1 hour. 3.84 g (10 mmol) ofCpODA-en1 was gradually added to the resulting solution. The mixture wasstirred at room temperature for 12 hours, to provide a homogeneous andviscous polyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-2.

Example 14

CpODA-en1 was provided as the tetracarboxylic acid component. 2.05 g (9mmol) of DABAN and 0.35 g (1 mmol) of FDA were placed in a reactionvessel, which was purged with nitrogen gas, and 24.96 g ofN-methyl-2-pyrrolidone was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 20 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en1 was graduallyadded to the resulting solution. The mixture was stirred at roomtemperature for 12 hours, to provide a homogeneous and viscous polyimideprecursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-2.

Example 15

CpODA-en1 was provided as the tetracarboxylic acid component. 3.12 g (9mmol) of 4-APTP and 0.35 g (1 mmol) of FDA were placed in a reactionvessel, which was purged with nitrogen gas, and 33.30 g ofN-methyl-2-pyrrolidone was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 18 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en1 was graduallyadded to the resulting solution. The mixture was stirred at roomtemperature for 12 hours, to provide a homogeneous and viscous polyimideprecursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-2.

Example 16

CpODA-en1 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN, 0.54 g (5 mmol) of PPD and 0.35 g (1 mmol) of FDA wereplaced in a reaction vessel, which was purged with nitrogen gas, and24.04 g of N-methyl-2-pyrrolidone was added thereto such that the totalmass of loading monomers (total mass of the diamine component and thecarboxylic acid component) was 19 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en1was gradually added to the resulting solution. The mixture was stirredat room temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-2.

Example 17

CpODA-en1 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN and 0.65 g (6 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 26.60 g ofN-methyl-2-pyrrolidone was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 18 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en1 was graduallyadded to the resulting solution. The mixture was stirred at roomtemperature for 12 hours, to provide a homogeneous and viscous polyimideprecursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-2.

Example 18

CpODA-en1 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN, 0.22 g (2 mmol) of PPD and 1.28 g (4 mmol) of TFMB wereplaced in a reaction vessel, which was purged with nitrogen gas, and22.16 g of N-methyl-2-pyrrolidone was added thereto such that the totalmass of loading monomers (total mass of the diamine component and thecarboxylic acid component) was 22 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en1was gradually added to the resulting solution. The mixture was stirredat room temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-2.

Example 19

CpODA-en2 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN and 0.65 g (6 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 26.60 g ofN-methyl-2-pyrrolidone was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 18 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en2 was graduallyadded to the resulting solution. The mixture was stirred at roomtemperature for 12 hours, to provide a homogeneous and viscous polyimideprecursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-2.

Example 20

CpODA-en3 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN and 0.65 g (6 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 26.60 g ofN-methyl-2-pyrrolidone was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 18 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en3 was graduallyadded to the resulting solution. The mixture was stirred at roomtemperature for 12 hours, to provide a homogeneous and viscous polyimideprecursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-2.

Example 21

CpODA-en4 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN and 0.65 g (6 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 26.60 g ofN-methyl-2-pyrrolidone was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 18 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4 was graduallyadded to the resulting solution. The mixture was stirred at roomtemperature for 12 hours, to provide a homogeneous and viscous polyimideprecursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-3.

Example 22

CpODA-en4 was provided as the tetracarboxylic acid component. 2.27 g (10mmol) of DABAN was placed in a reaction vessel, which was purged withnitrogen gas, and 29.83 g of N-methyl-2-pyrrolidone was added theretosuch that the total mass of loading monomers (total mass of the diaminecomponent and the carboxylic acid component) was 17 mass %, and then themixture was stirred at room temperature for 1 hour. 3.84 g (10 mmol) ofCpODA-en4 was gradually added to the resulting solution. The mixture wasstirred at room temperature for 12 hours, to provide a homogeneous andviscous polyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-3.

Example 231

CpODA-en4 was provided as the tetracarboxylic acid component. 1.59 g (7mmol) of DABAN and 0.32 g (3 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 28.07 g ofN-methyl-2-pyrrolidone was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 17 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4 was graduallyadded to the resulting solution. The mixture was stirred at roomtemperature for 12 hours, to provide a homogeneous and viscous polyimideprecursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-3.

Example 24

CpODA-en4 was provided as the tetracarboxylic acid component. 1.59 g (7mmol) of DABAN and 0.96 g (3 mmol) of TFMB were placed in a reactionvessel, which was purged with nitrogen gas, and 25.56 g ofN-methyl-2-pyrrolidone was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 20 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4 was graduallyadded to the resulting solution. The mixture was stirred at roomtemperature for 12 hours, to provide a homogeneous and viscous polyimideprecursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-3.

Example 25

CpODA-en4 was provided as the tetracarboxylic acid component. 1.14 g (5mmol) of DABAN, 0.43 g (4 mmol) of PPD and 0.20 g (1 mmol) of 4,4′-ODAwere placed in a reaction vessel, which was purged with nitrogen gas,and 27.39 g of N-methyl-2-pyrrolidone was added thereto such that thetotal mass of loading monomers (total mass of the diamine component andthe carboxylic acid component) was 17 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4was gradually added to the resulting solution. The mixture was stirredat room temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor solution was heated on the glass substrate from roomtemperature to 420° C. in a nitrogen atmosphere (oxygen concentration:200 ppm or less), to provide a colorless and transparent polyimidefilm/glass laminate.

Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-3.

Example 26

CpODA-en4 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN, 0.43 g (4 mmol) of PPD and 0.64 g (2 mmol) of TFMB wereplaced in a reaction vessel, which was purged with nitrogen gas, and23.28 g of N-methyl-2-pyrrolidone was added thereto such that the totalmass of loading monomers (total mass of the diamine component and thecarboxylic acid component) was 20 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4was gradually added to the resulting solution. The mixture was stirredat room temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-3.

Example 27

CpODA-en4 was provided as the tetracarboxylic acid component. 1.73 g (5mmol) of 4-APTP and 1.60 g (5 mmol) of TFMB were placed in a reactionvessel, which was purged with nitrogen gas, and 28.68 g ofN,N-dimethylacetamide was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 20 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4 was graduallyadded to the resulting solution. The mixture was stirred at roomtemperature for 12 hours, to provide a homogeneous and viscous polyimideprecursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-3.

Example 281

CpODA-en4 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN, 0.54 g (5 mmol) of PPD and 0.37 g (1 mmol) of BAPB wereplaced in a reaction vessel, which was purged with nitrogen gas, and22.64 g of N-methyl-2-pyrrolidone was added thereto such that the totalmass of loading monomers (total mass of the diamine component and thecarboxylic acid component) was 20 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4was gradually added to the resulting solution. The mixture was stirredat room temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-3.

Example 29

CpODA-en4 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN, 0.54 g (5 mmol) of PPD and 0.29 g (1 mmol) of TPE-R wereplaced in a reaction vessel, which was purged with nitrogen gas, and25.42 g of N-methyl-2-pyrrolidone was added thereto such that the totalmass of loading monomers (total mass of the diamine component and thecarboxylic acid component) was 18 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4was gradually added to the resulting solution. The mixture was stirredat room temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-3.

Example 30

CpODA-en4 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN, 0.54 g (5 mmol) of PPD and 0.11 g (1 mmol) of MPD wereplaced in a reaction vessel, which was purged with nitrogen gas, and24.60 g of N-methyl-2-pyrrolidone was added thereto such that the totalmass of loading monomers (total mass of the diamine component and thecarboxylic acid component) was 18 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4was gradually added to the resulting solution. The mixture was stirredat room temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-3.

Example 31

CpODA-en4 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN, 0.32 g (3 mmol) of PPD and 0.32 g (3 mmol) of MPD wereplaced in a reaction vessel, which was purged with nitrogen gas, and24.55 g of N-methyl-2-pyrrolidone was added thereto such that the totalmass of loading monomers (total mass of the diamine component and thecarboxylic acid component) was 18 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4was gradually added to the resulting solution. The mixture was stirredat room temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-3.

Example 32

CpODA-en4 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN, 0.54 g (5 mmol) of PPD and 0.20 g (1 mmol) of 3,4′-ODAwere placed in a reaction vessel, which was purged with nitrogen gas,and 25.01 g of N-methyl-2-pyrrolidone was added thereto such that thetotal mass of loading monomers (total mass of the diamine component andthe carboxylic acid component) was 18 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4was gradually added to the resulting solution. The mixture was stirredat room temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-3.

Example 33

CpODA-en4 was provided as the tetracarboxylic acid component. 0.68 g (3mmol) of DABAN, 0.65 g (6 mmol) of PPD and 0.37 g (1 mmol) of BAPB wereplaced in a reaction vessel, which was purged with nitrogen gas, and29.09 g of N-methyl-2-pyrrolidone was added thereto such that the totalmass of loading monomers (total mass of the diamine component and thecarboxylic acid component) was 16 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4was gradually added to the resulting solution. The mixture was stirredat room temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 410°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 km.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-4.

Example 34

CpODA-en4 was provided as the tetracarboxylic acid component. 0.45 g (2mmol) of DABAN, 0.76 g (7 mmol) of PPD and 0.37 g (1 mmol) of BAPB wereplaced in a reaction vessel, which was purged with nitrogen gas, and28.46 g of N-methyl-2-pyrrolidone was added thereto such that the totalmass of loading monomers (total mass of the diamine component and thecarboxylic acid component) was 16 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4was gradually added to the resulting solution. The mixture was stirredat room temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 410°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-4.

Example 351

CpODA-en4 was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN, 0.54 g (5 mmol) of PPD and 0.22 g (1 mmol) of ASD wereplaced in a reaction vessel, which was purged with nitrogen gas, and28.93 g of N-methyl-2-pyrrolidone was added thereto such that the totalmass of loading monomers (total mass of the diamine component and thecarboxylic acid component) was 16 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.84 g (10 mmol) of CpODA-en4was gradually added to the resulting solution. The mixture was stirredat room temperature for 12 hours, to provide a homogeneous and viscouspolyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor solution was heated on the glass substrate from roomtemperature to 410° C. in a nitrogen atmosphere (oxygen concentration:200 ppm or less), to provide a colorless and transparent polyimidefilm/glass laminate.

Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-4.

Example 361

CpODA-en4 and DNDAxx were provided as the tetracarboxylic acidcomponent. 0.91 g (4 mmol) of DABAN and 0.65 g (6 mmol) of PPD wereplaced in a reaction vessel, which was purged with nitrogen gas, and27.93 g of N-methyl-2-pyrrolidone was added thereto such that the totalmass of loading monomers (total mass of the diamine component and thecarboxylic acid component) was 16 mass %, and then the mixture wasstirred at room temperature for 1 hour. 3.46 g (9 mmol) of CpODA-en4 and0.30 g (1 mmol) of DNDAxx were gradually added to the resultingsolution. The mixture was stirred at room temperature for 12 hours, toprovide a homogeneous and viscous polyimide precursor solution.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor solution was heated on the glass substrate from roomtemperature to 410° C. in a nitrogen atmosphere (oxygen concentration:200 ppm or less), to provide a colorless and transparent polyimidefilm/glass laminate.

Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-1-4.

Comparative Example 1

CpODA was provided as the tetracarboxylic acid component. 2.27 g (10mmol) of DABAN was placed in a reaction vessel, which was purged withnitrogen gas, and 17.41 g of N,N-dimethylacetamide was added theretosuch that the total mass of loading monomers (total mass of the diaminecomponent and the carboxylic acid component) was 26 mass %, and then themixture was stirred at room temperature for 1 hour. 3.84 g (10 mmol) ofCpODA was gradually added to the resulting solution. The mixture wasstirred at room temperature for 12 hours, to provide a homogeneous andviscous polyimide precursor solution. The logarithmic viscosity of theobtained polyimide precursor was 1.0 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-2.

Comparative Example 21

CpODA was provided as the tetracarboxylic acid component. 2.12 g (10mmol) of m-TD was placed in a reaction vessel, which was purged withnitrogen gas, and 27.18 g of N,N-dimethylacetamide was added theretosuch that the total mass of loading monomers (total mass of the diaminecomponent and the carboxylic acid component) was 18 mass %, and then themixture was stirred at room temperature for 1 hour. 3.84 g (10 mmol) ofCpODA was gradually added to the resulting solution. The mixture wasstirred at room temperature for 12 hours, to provide a homogeneous andviscous polyimide precursor solution. The logarithmic viscosity of theobtained polyimide precursor was 1.9 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-2.

Comparative Example 3

CpODA was provided as the tetracarboxylic acid component. 3.48 g (10mmol) of BAPT was placed in a reaction vessel, which was purged withnitrogen gas, and 38.47 g of N,N-dimethylacetamide was added theretosuch that the total mass of loading monomers (total mass of the diaminecomponent and the carboxylic acid component) was 16 mass %, and then themixture was stirred at room temperature for 1 hour. 3.84 g (10 mmol) ofCpODA was gradually added to the resulting solution. The mixture wasstirred at room temperature for 12 hours, to provide a homogeneous andviscous polyimide precursor solution. The logarithmic viscosity of theobtained polyimide precursor was 2.5 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-2.

Comparative Example 4

CpODA was provided as the tetracarboxylic acid component. 1.14 g (5mmol) of DABAN and 1.60 g (5 mmol) of TFMB were placed in a reactionvessel, which was purged with nitrogen gas, and 16.34 g ofN,N-dimethylacetamide was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 25 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA was gradually added tothe resulting solution. The mixture was stirred at room temperature for12 hours, to provide a homogeneous and viscous polyimide precursorsolution. The logarithmic viscosity of the obtained polyimide precursorwas 0.2 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-2.

Comparative Example 51

CpODA was provided as the tetracarboxylic acid component. 1.59 g (7mmol) of DABAN and 0.96 g (3 mmol) of TFMB were placed in a reactionvessel, which was purged with nitrogen gas, and 18.07 g ofN,N-dimethylacetamide was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 21 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA was gradually added tothe resulting solution. The mixture was stirred at room temperature for12 hours, to provide a homogeneous and viscous polyimide precursorsolution. The logarithmic viscosity of the obtained polyimide precursorwas 0.4 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-2.

Comparative Example 6

CpODA was provided as the tetracarboxylic acid component. 1.59 g (7mmol) of DABAN and 0.32 g (3 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 11.86 g ofN,N-dimethylacetamide was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 26 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA was gradually added tothe resulting solution. The mixture was stirred at room temperature for12 hours, to provide a homogeneous and viscous polyimide precursorsolution. The logarithmic viscosity of the obtained polyimide precursorwas 1.2 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-2.

Comparative Example 7

CpODA was provided as the tetracarboxylic acid component. 1.14 g (5mmol) of DABAN and 0.54 g (5 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 13.15 g ofN,N-dimethylacetamide was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 25 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA was gradually added tothe resulting solution. The mixture was stirred at room temperature for12 hours, to provide a homogeneous and viscous polyimide precursorsolution. The logarithmic viscosity of the obtained polyimide precursorwas 1.1 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-2.

Comparative Example 8

CpODA was provided as the tetracarboxylic acid component. 0.91 g (4mmol) of DABAN and 0.65 g (6 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 24.60 g ofN-methyl-2-pyrrolidone was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 18 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA was gradually added tothe resulting solution. The mixture was stirred at room temperature for12 hours, to provide a homogeneous and viscous polyimide precursorsolution. The logarithmic viscosity of the obtained polyimide precursorwas 0.8 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-2.

Comparative Example 9

CpODA was provided as the tetracarboxylic acid component. 0.68 g (3mmol) of DABAN and 0.76 g (7 mmol) of PPD were placed in a reactionvessel, which was purged with nitrogen gas, and 19.61 g ofN,N-dimethylacetamide was added thereto such that the total mass ofloading monomers (total mass of the diamine component and the carboxylicacid component) was 19 mass %, and then the mixture was stirred at roomtemperature for 1 hour. 3.84 g (10 mmol) of CpODA was gradually added tothe resulting solution. The mixture was stirred at room temperature for12 hours, to provide a homogeneous and viscous polyimide precursorsolution. The logarithmic viscosity of the obtained polyimide precursorwas 1.1 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-2.

Comparative Example 10

CpODA was provided as the tetracarboxylic acid component. 2.00 g (10mmol) of 4,4′-ODA was placed in a reaction vessel, which was purged withnitrogen gas, and 21.97 g of N,N-dimethylacetamide was added theretosuch that the total mass of loading monomers (total mass of the diaminecomponent and the carboxylic acid component) was 21 mass %, and then themixture was stirred at room temperature for 1 hour. 3.84 g (10 mmol) ofCpODA was gradually added to the resulting solution. The mixture wasstirred at room temperature for 12 hours, to provide a homogeneous andviscous polyimide precursor solution. The logarithmic viscosity of theobtained polyimide precursor was 1.6 dL/g.

The polyimide precursor solution, which was filtered through a PTFEmembrane filter, was applied on a glass substrate, and then thepolyimide precursor was thermally imidized by heating the polyimideprecursor solution on the glass substrate from room temperature to 420°C. in a nitrogen atmosphere (oxygen concentration: 200 ppm or less), toprovide a colorless and transparent polyimide film/glass laminate.Subsequently, the obtained polyimide film/glass laminate was immersed inwater, and then the polyimide film was peeled from the glass and dried,to provide a polyimide film having a thickness of about 10 μm.

The results of the measurements of the properties of the polyimide filmare shown in Table 2-2.

TABLE 2-1-1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Polyimide precursor Tetracarboxylic CpODA-en 10 10 10 10 10 10 acidcomponent CpODA-en1 (mmol) CpODA-en2 CpODA-en3 CpODA-en4 CpODA DNDAxxDiamine DABAN 10 5 7 component TFMB 5 3 (mmol) PPD m-TD 10 BAPT 104-APTP 10 FDA 4,4′-ODA BAPB TPE-R MPD 3,4′-ODA ASD Polyimide film Lighttransmittance at 400 nm, T₁ (%) 74 81 71 52 77 77 Total lighttransmittance, T₂ (%) 85 89 86 85 87 86 Modulus of elasticity (GPa) 6.05.2 5.4 7.3 4.2 5.0 Elongation at break (%) 6 10 11 13 20 13 Coefficientof linear thermal 10 45 26 8 28 25 expansion (ppm/K) (50-400° C.) 5%weight loss temperature (° C.) 503 472 485 500 490 488 Example ExampleExample Example 7 Example 8 Example 9 10 11 12 Polyimide precursorTetracarboxylic CpODA-en 10 10 10 10 10 10 acid component CpODA-en1(mmol) CpODA-en2 CpODA-en3 CpODA-en4 CpODA DNDAxx Diamine DABAN 7 5 4 34 5 component TFMB 2 (mmol) PPD 3 5 6 7 4 4 m-TD BAPT 4-APTP FDA4,4′-ODA 1 BAPB TPE-R MPD 3,4′-ODA ASD Polyimide film Lighttransmittance at 400 nm, T₁ (%) 77 79 80 80 79 79 Total lighttransmittance, T₂ (%) 87 88 88 87 86 87 Modulus of elasticity (GPa) 6.05.6 5.3 4.9 5.2 5.5 Elongation at break (%) 8 8 6 6 13 13 Coefficient oflinear thermal 18 20 15 24 26 22 expansion (ppm/K) (50-400° C.) 5%weight loss temperature (° C.) 492 492 504 495 488 497

TABLE 2-1-2 Example Example Example Example Example Example ExampleExample 13 14 15 16 17 18 19 20 Polyimide precursor TetracarboxylicCpODA-en acid component CpODA-en1 10 10 10 10 10 10 (mmol) CpODA-en2 10CpODA-en3 10 CpODA-en4 CpODA DNDAxx Diamine DABAN 9 4 4 4 4 4 componentTFMB 4 (mmol) PPD 5 6 2 6 6 m-TD BAPT 4-APTP 10 9 FDA 1 1 1 4,4′-ODABAPB TPE-R MPD 3,4′-ODA ASD Polyimide film Light transmittance at 400nm, T₁ (%) 52 78 60 85 80 84 82 77 Total light transmittance, T₂ (%) 8588 86 88 87 88 87 87 Modulus of elasticity (GPa) 5.7 4.1 5.2 3.3 4.4 3.35.6 5.5 Elongation at break (%) 15 4 14 8 10 23 5 7 Coefficient oflinear thermal 13 32 12 43 24 42 18 16 expansion (ppm/K) (50-400° C.) 5%weight loss temperature (° C.) 504 500 501 500 502 — — —

TABLE 2-1-3 Example Example Example Example Example Example 21 22 23 2425 26 Polyimide precursor Tetracarboxylic CpODA-en acid componentCpODA-en1 (mmol) CpODA-en2 CpODA-en3 CpODA-en4 10 10 10 10 10 10 CpODADNDAxx Diamine DABAN 4 10 7 7 5 4 component TFMB 3 2 (mmol) PPD 6 3 4 4m-TD BAPT 4-APTP FDA 4,4′-ODA 1 BAPB TPE-R MPD 3,4′-ODA ASD Polyimidefilm Light transmittance at 400 nm, T₁ (%) 78 75 78 76 79 79 Total lighttransmittance, T₂ (%) 87 86 86 86 87 87 Modulus of elasticity (GPa) 5.67.3 6.6 6.2 6.6 5.7 Elongation at break (%) 8 9 5 9 9 7 Coefficient oflinear thermal 14 12 13 28 15 17 expansion (ppm/K) (50-400° C.) 5%weight loss temperature (° C.) — 505 504 496 504 497 Example ExampleExample Example Example Example 27 28 29 30 31 32 Polyimide precursorTetracarboxylic CpODA-en acid component CpODA-en1 (mmol) CpODA-en2CpODA-en3 CpODA-en4 10 10 10 10 10 10 CpODA DNDAxx Diamine DABAN 4 4 4 44 component TFMB 5 (mmol) PPD 5 5 5 3 5 m-TD BAPT 4-APTP 5 FDA 4,4′-ODABAPB 1 TPE-R 1 MPD 1 3 3,4′-ODA 1 ASD Polyimide film Light transmittanceat 400 nm, T₁ (%) 75 75 74 76 81 76 Total light transmittance, T₂ (%) 8685 85 86 88 86 Modulus of elasticity (GPa) 6.5 5.6 5.5 5.7 5 5.6Elongation at break (%) 18 13 8 6 5 11 Coefficient of linear thermal 2218 23 21 22 18 expansion (ppm/K) (50-400° C.) 5% weight loss temperature(° C.) 493 504 501 501 499 501

TABLE 2-1-4 Exam- Exam- Exam- Exam- ple 33 ple 34 ple 35 ple 36Polyimide precursor Tetra- CpODA-en carboxylic CpODA-en1 acid CpODA-en2component CpODA-en3 (mmol) CpODA-en4 10 10 10 9 CpODA DNDAxx 1 DiamineDABAN 3 2 4 4 component TFMB (mmol) PPD 6 7 5 6 m-TD BAPT 4-APTP FDA4,4′-ODA BAPB 1 1 TPE-R MPD 3,4′-ODA ASD 1 Polyimide film Lighttransmit- 76 77 71 77 tance at 400 nm, T₁ (%) Total light 86 87 86 87transmittance, T₂ (%) Modulus of 5.4 5.1 5.4 5.7 elasticity (GPa)Elongation at 15 9 4 8 break (%) Coefficient of 18 21 19 16 linearthermal expansion (ppm/K) (50-400° C.) 5% weight loss — — 492 —temperature (° C.)

TABLE 2-2 Comparative Comparative Comparative Comparative ComparativeExample 1 Example 2 Example 3 Example 4 Example 5 Polyimide precursorTetracarboxylic CpODA-en acid component CpODA-en1 (mmol) CpODA-en2CpODA-en3 CpODA-en4 CpODA 10 10 10 10 10 DNDAxx Diamine DABAN 10 5 7component TFMB 5 3 (mmol) PPD m-TD 10 BAPT 10 4-APTP FDA 4,4′-ODA BAPBTPE-R MPD 3,4′-ODA ASD Polyimide film Light transmittance at 400 nm, T₁(%) 72 86 73 83 82 Total light transmittance, T₂ (%) 83 88 84 89 87Modulus of elasticity (GPa) 5.2 4.4 5.0 3.4 3.6 Elongation at break (%)13 30 9 35 24 Coefficient of linear thermal 16 66 27 62 48 expansion(ppm/K) (50-400° C.) 5% weight loss temperature (° C.) 497 474 475 483484 Comparative Comparative Comparative Comparative Comparative Example6 Example 7 Example 8 Example 9 Example 10 Polyimide precursorTetracarboxylic CpODA-en acid component CpODA-en1 (mmol) CpODA-en2CpODA-en3 CpODA-en4 CpODA 10 10 10 10 10 DNDAxx Diamine DABAN 7 5 4 3component TFMB (mmol) PPD 3 5 6 7 m-TD BAPT 4-APTP FDA 4,4′-ODA 10 BAPBTPE-R MPD 3,4′-ODA ASD Polyimide film Light transmittance at 400 nm, T₁(%) 80 82 81 83 79 Total light transmittance, T₂ (%) 86 88 88 87 86Modulus of elasticity (GPa) 5.5 4.0 4.2 4.7 2.3 Elongation at break (%)15 18 11 13 78 Coefficient of linear thermal 24 26 26 30 117 expansion(ppm/K) (50-400° C.) 5% weight loss temperature (° C.) 496 496 502 496490

As can be seen from the results shown in Tables 2-1-1 to 2-1-4 and Table2-2, the polyimides of the present invention have a small coefficient oflinear thermal expansion up to a high temperature, specifically from 50°C. to 400° C. (Examples 1, 22 and Comparative Example 1, Example 2 andComparative Example 2, Example 3 and Comparative Example 3, Example 5and Comparative Example 4, Examples 6, 24 and Comparative Example 5,Examples 7, 23 and Comparative Example 6, Example 8 and ComparativeExample 7, Examples 9, 17, 19, 20, 21 and Comparative Example 8, Example10 and Comparative Example 9).

When DABAN, BAPT or 4-APTP is used as the diamine component, inparticular, the coefficient of linear thermal expansion is very small(Examples 1, 3, 4, 13 and 22). Meanwhile, when TFMB and/or PPD, andDABAN are copolymerized, the polyimide exhibits very low thermalexpansibility up to a high temperature, and high transparency (Examples5 to 12, 14, 16 to 21, 23 to 26, and 28 to 36).

As described above, the polyimide obtained from the polyimide precursorof the present invention has excellent optical transparency and bendingresistance, and has a low coefficient of linear thermal expansion up toa high temperature, and therefore the polyimide film of the presentinvention may be suitably used as a transparent substrate for use in adisplay, and the like, which is colorless and transparent, and on whicha fine circuit can be formed.

INDUSTRIAL APPLICABILITY

According to the present invention, there may be provided a polyimidehaving excellent properties such as transparency, bending resistance andhigh heat resistance, and having a very low coefficient of linearthermal expansion up to a high temperature; and a precursor thereof. Thepolyimide obtained from the polyimide precursor, and the polyimide havehigh transparency and a low coefficient of linear thermal expansion upto a high temperature, which allows easy formation of a fine circuit,and have solvent resistance, and therefore the polyimides may besuitably used for the formation of a substrate for use in a display, orthe like, in particular.

1. A polyimide precursor comprising at least one repeating unitrepresented by the following chemical formula (1):

wherein A₁ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed; and X₁ and Y₁ areeach independently hydrogen, an alkyl group having 1 to 6 carbon atoms,or an alkylsilyl group having 3 to 9 carbon atoms, wherein the totalcontent of the repeating units represented by the chemical formula (1)is 50 mol % or more based on the total repeating units.
 2. The polyimideprecursor according to claim 1, wherein the polyimide precursorcomprises at least one repeating unit of the chemical formula (1) inwhich A₁ is a group represented by the following chemical formula (2):

wherein m₁ and n₁ are integers of 0 or more, and m₁ independentlyrepresents 0 to 3 and n₁ independently represents 0 to 3; V₁, U₁ and T₁each independently represent at least one selected from the groupconsisting of hydrogen atom, methyl group and trifluoromethyl group; andZ₁ and W₁ each independently represent direct bond, or at least oneselected from the group consisting of groups represented by theformulas: —NHCO—, —CONH—, —COO— and —OCO—.
 3. The polyimide precursoraccording to claim 2, wherein the polyimide precursor comprises at leasttwo of repeating units of the chemical formula (1) in which A₁ is agroup represented by the chemical formula (2).
 4. A polyimide precursorcomprising at least one repeating unit represented by the followingchemical formula (3):

wherein A₂ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed; and X₂ and Y₂ areeach independently hydrogen, an alkyl group having 1 to 6 carbon atoms,or an alkylsilyl group having 3 to 9 carbon atoms, wherein the totalcontent of the repeating units represented by the chemical formula (3)is 30 mol % or more based on the total repeating units.
 5. The polyimideprecursor according to claim 4, wherein the polyimide precursorcomprises at least one repeating unit of the chemical formula (3) inwhich A₂ is a group represented by the following chemical formula (4):

wherein m₂ and n₂ are integers of 0 or more, and m₂ independentlyrepresents 0 to 3 and n₂ independently represents 0 to 3; V₂, U₂ and T₂each independently represent at least one selected from the groupconsisting of hydrogen atom, methyl group and trifluoromethyl group; andZ₂ and W₂ each independently represent direct bond, or at least oneselected from the group consisting of groups represented by theformulas: —NHCO—, —CONH—, —COO— and —OCO—.
 6. The polyimide precursoraccording to claim 5, wherein the polyimide precursor comprises at leasttwo of repeating units of the chemical formula (3) in which A₂ is agroup represented by the chemical formula (4).
 7. A polyimide precursorcomprising at least one of repeating units represented by the followingchemical formula (5) and the following chemical formula (6):

wherein A₃ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed; and X₃ and Y₃ areeach independently hydrogen, an alkyl group having 1 to 6 carbon atoms,or an alkylsilyl group having 3 to 9 carbon atoms,

wherein A₃ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed; and X₄ and Y₄ areeach independently hydrogen, an alkyl group having 1 to 6 carbon atoms,or an alkylsilyl group having 3 to 9 carbon atoms, wherein the totalcontent of the repeating units represented by the chemical formula (5)and the chemical formula (6) is 80 mol % or more based on the totalrepeating units.
 8. The polyimide precursor according to claim 7,wherein the polyimide precursor comprises at least one repeating unit ofthe chemical formula (5) in which A₃ is a group represented by thefollowing chemical formula (7) and/or at least one repeating unit of thechemical formula (6) in which A₃ is a group represented by the followingchemical formula (7):

wherein m₃ and n₃ are integers of 0 or more, and m₃ independentlyrepresents 0 to 3 and n₃ independently represents 0 to 3; V₃, U₃ and T₃each independently represent at least one selected from the groupconsisting of hydrogen atom, methyl group and trifluoromethyl group; andZ₃ and W₃ each independently represent direct bond, or at least oneselected from the group consisting of groups represented by theformulas: —NHCO—, —CONH—, —COO— and —OCO—.
 9. The polyimide precursoraccording to claim 8, wherein the polyimide precursor comprises at leasttwo of repeating units of the chemical formula (5) or the chemicalformula (6) in which A₃ is a group represented by the chemical formula(7).
 10. The polyimide precursor according to claim 7, wherein the totalcontent of the repeating units represented by the chemical formula (5)is 50 mol % or more based on the total repeating units, and the totalcontent of the repeating units represented by the chemical formula (6)is 30 mol % or more based on the total repeating units.
 11. A polyimidecomprising at least one repeating unit represented by the followingchemical formula (8):

wherein B₁ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed, wherein the totalcontent of the repeating units represented by the chemical formula (8)is 50 mol % or more based on the total repeating units.
 12. Thepolyimide according to claim 11, wherein the polyimide comprises atleast one repeating unit of the chemical formula (8) in which B₁ is agroup represented by the following chemical formula (9):

wherein m₄ and n₄ are integers of 0 or more, and m₄ independentlyrepresents 0 to 3 and n₄ independently represents 0 to 3; V₄, U₄ and T₄each independently represent at least one selected from the groupconsisting of hydrogen atom, methyl group and trifluoromethyl group; andZ₄ and W₄ each independently represent direct bond, or at least oneselected from the group consisting of groups represented by theformulas: —NHCO—, —CONH—, —COO— and —OCO—.
 13. A polyimide comprising atleast one repeating unit represented by the following chemical formula(10):

wherein B₂ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed, wherein the totalcontent of the repeating units represented by the chemical formula (10)is 30 mol % or more based on the total repeating units.
 14. Thepolyimide according to claim 13, wherein the polyimide comprises atleast one repeating unit of the chemical formula (10) in which B₂ is agroup represented by the following chemical formula (11):

wherein m₅ and n₅ are integers of 0 or more, and m₅ independentlyrepresents 0 to 3 and n₅ independently represents 0 to 3; V₅, U₅ and T₅each independently represent at least one selected from the groupconsisting of hydrogen atom, methyl group and trifluoromethyl group; andZ₅ and W₅ each independently represent direct bond, or at least oneselected from the group consisting of groups represented by theformulas: —NHCO—, —CONH—, —COO— and —OCO—.
 15. A polyimide comprising atleast one of repeating units represented by the following chemicalformula (12) and the following chemical formula (13):

wherein B₃ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed,

wherein B₃ is a divalent group of an aromatic diamine or an aliphaticdiamine, from which amino groups have been removed, wherein the totalcontent of the repeating units represented by the chemical formula (12)and the chemical formula (13) is 80 mol % or more based on the totalrepeating units.
 16. The polyimide according to claim 15, wherein thepolyimide comprises at least one repeating unit of the chemical formula(12) in which B₃ is a group represented by the following chemicalformula (14) and/or at least one repeating unit of the chemical formula(13) in which B₃ is a group represented by the following chemicalformula (14):

wherein m₆ and n₆ are integers of 0 or more, and m₆ independentlyrepresents 0 to 3 and n₆ independently represents 0 to 3; V₆, U₆ and T₆each independently represent at least one selected from the groupconsisting of hydrogen atom, methyl group and trifluoromethyl group; andZ₆ and W₆ each independently represent direct bond, or at least oneselected from the group consisting of groups represented by theformulas: —NHCO—, —CONH—, —COO— and —OCO—.
 17. The polyimide accordingto claim 15, wherein the total content of the repeating unitsrepresented by the chemical formula (12) is 50 mol % or more based onthe total repeating units, and the total content of the repeating unitsrepresented by the chemical formula (13) is 30 mol % or more based onthe total repeating units.
 18. (canceled)
 19. (canceled)
 20. A varnishcomprising the polyimide precursor according to claim
 1. 21. A polyimidefilm obtained using a varnish comprising the polyimide precursoraccording to claim
 1. 22. A substrate for a display, a touch panel or asolar battery formed of the polyimide according to claim
 11. 23. Avarnish comprising the polyimide precursor according to claim
 4. 24. Avarnish comprising the polyimide precursor according to claim
 7. 25. Avarnish comprising the polyimide according to claim
 11. 26. A varnishcomprising the polyimide according to claim
 13. 27. A varnish comprisingthe polyimide according to claim
 15. 28. A polyimide film obtained usinga varnish comprising the polyimide precursor according to claim
 4. 29. Apolyimide film obtained using a varnish comprising the polyimideprecursor according to claim
 7. 30. A polyimide film obtained using avarnish comprising the polyimide according to claim
 11. 31. A polyimidefilm obtained using a varnish comprising the polyimide according toclaim
 13. 32. A polyimide film obtained using a varnish comprising thepolyimide according to claim
 15. 33. A substrate for a display, a touchpanel or a solar battery formed of the polyimide according to claim 13.34. A substrate for a display, a touch panel or a solar battery formedof the polyimide according to claim 15.